I just want a healthy democracy.
This is an interesting thing to look at comparatively, since often I see arguments that centered on the specifically American system which lack any consideration of at what else is possible. China and Russia are good examples of how this mentality of supporting "democracy" is so easily warped in way that can serve the underlying systems that actually matter (and fundamentally contradict the aims of democracy).
China is an interesting political case to consider, especially since the Chinese government gets so grossly simplified in the media. China has the most extensive elected legislatures in the world, with massive local, regional, and national bodies. The sitting members are elected by popular vote with a secret ballot for limited terms, and the candidates are nominated by a primary process based on nominations made by the public, run by officials who are themselves elected. There are 8 official parties and numerous independents (generally more common at the lower levels) and the national legislative body currently has 72% of seats filled by the CPC while the rest are occupied by other parties and independents (this at least somewhat contradicts the common image of a purely one-party state). Positions like mayors, important committee members, chairpersons, etc. are usually elected directly without an intermediary legislature, but generally the higher legislatures are drawn from members of the lower bodies. Many of the parties actively appeal to democracy, debate in the legislature occurs, and the government often appeals to democratic values.
And it's the biggest sham democracy in existence. China is one of the most authoritarian countries in the world, as nearly everyone outside of it knows. The government itself is largely a rubber stamp for policies created within the expansive parallel structures of the CPC (which has delegate bodies that exist in almost the same structure as the government at the local, regional, and national levels) and all power is held by small committees within the CPC, usually separate from government. And yet, most people in China will say that it's a "healthy democracy" with which they are content, and by all appearances from within it is, because they don't have the opportunity to compare their system to others and see what a lie it is. They regularly vote under free conditions selecting candidates according to their preference, but any critical examination reveals what a waste this voting is, and how the whole process transparently only exists to absorb political energy and keep the ruling clique from becoming too degenerate and out of touch. What's really incredible about the Chinese system, however, is that it doesn't even rely much on coercion or true totalitarianism; the people believe it works and the system is legitimate, and so it is.
Example two, Russia. Russia has a constitution that's modeled after that of France, which incidentally has a horrible system that mixes the power of an elected president with that of a head of government representing the legislature. When I say "modeled after", I mean copy-pasted. Russia and France have basically identical government frameworks. And yet, Russia's government and politics looks radically different. Here too people regularly vote, regularly critically examine their options that are presented to them (of which there are many) but in the end the same dominant party system keeps on trucking as it does in China. The alternatives to United Russia are jokes without punchlines who like the minor parties in China exist at the pleasure of the ruling clique, often literally in financial dependence on their ostensible opponents. People in Russia in general are contented with voting for United Russia, because the alternatives are usually worse and their stated policies are acceptable enough. Compared to China, however, Russia lacks a formal ideological structure apparatus that enforces this system. The ruling body in Russia are the oligarchs who illegally partitioned the extensive state-owned property and capital of the USSR during its chaotic dissolution, unlike China that has a massive formal party structure behind it. Protection of the oligarchs is the raison d'etre for the Russian government to exist, and the government relies on extralegal means (actual murders and vote-rigging) and state propaganda to keep the system going, arguably to a greater extent than China. But for the voters, it's a "healthy democracy" that enjoys genuine popularity, or at the very least isn't seen as much worse than the shams in the West. The government is elected, the voting rituals are held, and overwhelmingly people passively accept the outcomes.
The point of these two examples is that it is readily obvious that voting within these systems is a pointless endeavor incapable of effecting political change, and worse than that it the elections serve a negative purpose in deluding people into thinking they live in a "healthy democracy" or that it's even possible. People spend their lives running in circles that have been deliberately laid out for them, passively accepting results that were rigged against them from the start without needing any foul play. What would need to change for the same to be obviously true in the US? Both these example countries rely heavily on "soft" influences (every country in the world stays in power almost exclusively on soft terms), and so does the ruling body of the US. All three countries have systems that are superficially in line with what we would consider democratic structures, at least enough for the average person to buy into them, but where precisely in the details do the irregularities emerge? This is why I often blabber so much about this crap, anyway, because it's at least rhetorically worth considering.
You're imagining some sort of perfect gerrymander, but this is unreal. Federal-level Gerrymanders in this country last for at most 10 years and any demographic changes which occur within that time weaken the gerrymander. People are born, come of age, and die, and opinions shift. The government doesn't have the power to make unlimited districts at any time and that and other "hard" restrictions on gerrymandering (as opposed to "soft" restrictions like court-challenges) impose a hardcap on the degree of successful gerrymandering. Again, you're assuming perfect knowledge of people's political preferences perfect stasis, and perfect freedom to create and shape districts, and yes in that system a party can be completely disenfranchised forever. The current system cannot be gerrymandered to that level and to focus on that is misleading, since it ignores situations where gerrymanders are overcome (which does happen!). Finally, by fixateing on parties, you ignore the specter of so-called "bipartisan gerrymandering", where states are redrawn specifically to defend incumbents. This does not disadvantage either party more or less than it is already ss under the previous system, but there are losers. There are sub-party movements, for example, or bipartisan issues. But this is Devil's advocate stuff here, I agree with you but I see your point as complementary rather than contradictory.
I used edge cases of perfect gerrymandering examples to illustrate what "wasted votes" are and why it's important (my original post was deliberately unclear to maximize dumb snark). Most of the vote wasting in the US doesn't happen due to deliberate gerrymandering, it's just an accidental product of the system. People move to areas where they're immediately surrounded by others that they agree with, and since district lines are drawn geographically a result is that the "packing" of districts occurs "voluntarily" (obviously none of this happens with popular consent or their being informed). Presumably, one small reason why people concentrate themselves in this way is because they know that their votes are worthless in areas where they're a minority and are sick of being "represented" for decades on end by a jackass they loathe.
However, the future is going to look more perfectly gerrymandered, if the courts don't succeed in fully preventing it (or some political catastrophe upsets the whole system). The last cycle of apportionment and districting brought with it an unprecedented amount of coordinated gerrymandering informed by more accurate models than ever before, which will have improved further by the time of the next cycle.
The chief effect usually considered of these "wasted votes" is that they create disproportional outcomes (national seat percentages do not match national vote percentages, which is exactly how the Republicans control all three branches right now incidentally), and this is emphasized in part because it's an effect that's very easy to demonstrate mathematically and obvious in its implications. The problems go deeper, however. The whole ostensible point of our horrible system is that federal representatives are supposed to have a direct connection back to a local population whose interests they represent. This is not only dubiously beneficial in the first place (in effect it just creates a perverse motive for the representatives to fleece the federal government in favor of pork for their district), it's not even remotely achieved, in part for the reasons you listed. The districts are redrawn regularly and are impossible to be drawn objectively, and lump together populations in totally arbitrary configurations that are rarely able to reflect any nuance. The people themselves move regularly and there is little peculiarly unique about any of these arbitrarily drawn collections of populations. The people in charge of the system use it for their own ends, and are unlikely to ever support improving it. By having a system like this more generally, it creates a political dead zone in 2/3 to 3/4 of the country where elections are settled with certainty in the primaries, while the remaining seats that are close enough to be competitive are the sites of massive influxes of campaign spending from national interests. Most of the country lives in a congressional fiefdom prone to embarrassing amounts of incompetence and unaccountability, while the few who by accident have a vote that matters have their "local" campaign dominated by the needs of the national party strategy and the interests backing them. Under this system, every voter is either taken for granted, ignored completely, or harassed, cajoled, and pandered to with every legally available means for the brief time that their vote is suddenly relevant. The massive district sizes preclude any possibility of minority political groups winning seats and ensure a permanent two-party system that remains the subject of completely justified apathy, contempt, and disbelief in the legitimacy of the system. Most people vote against the party they hate rather than for the party they like, but become vessels for their ideology nonetheless which is the only thing that ever gets media exposure.
The core, overarching point here is that the vote is not a remotely effective means of exerting political influence, and in systems that as much of a sham as ours it's not even feasible to groups to effectively influence the system that passively.