That's actually unlikely about the inflation. If they're doing the math today, they're almost certainly calculating it in today-dollars rather than hypotetical actual 2050 dollars. There's no way that could be part of their calculation.
And that is not the full cost saved, it's the incremental saving of doing that policy change. The good news is that economics is doing some of the heavy-lifting for us already. Additionally, those costs wouldn't be evenly distributed among the years, they'd be more costly towards the end. So assuming the policy takes 15 years to be enacted (since it says 2035 to kick in) then the saving are after that, so 15 years = $333 per year per person in higher taxes and/or premiums. But you'd have to account for inflation on that figure too, and young people will be boomer-aged by then, so it's coming out of the money you're earning now, but with inflation, and at a time when saving interest rates are basically in the toilet. Damn straight and extra $333 per year in costs would fuck over a lot of people. Additionally "health and environmental costs" only covers a part of the impact. There's lost employment and productivity associated too, plenty of other externalities we're not taking into account for not dealing with the problem. Those other costs may dwarf the direct health and environmental costs.
Although I don't actually think the scale of the savings is the reason people don't do these things. Remember stuff like Nash Equilibriums etc. Even if the overall savings are HUGE, nobody has a specific incentive to be the one that starts it. The reason they don't is that if I reduce my emissions, it helps me a little, but less than the amount it costs me to reduce my emissions. But my emission reduction also helps everyone else out a little, and the fact is that if we all do it, we all save a lot of money overall. However, when you do a pay-off matrix from any one person's point of view, it's always economically better to not go along with the emission reductions. Either short term or long term.
Say as an example that your health insurance costs $10000, and emission-reduction costs $100, and if every did that, then insurance costs would be reduced to $5000, also say that the health savings from any one choice are spread over 5000 people. So, overall everyone spending $100 each sounds like a good idea right? Everyone saves 50 times as much as the investment costs. Yet, the Nash Equilibrium says otherwise:
Scenario 1) Say nobody else gets the emission reduction tech. You could spend nothing, and pay $10000 on premiums, or you could spend $100 and pay $9999 on premiums. You work out you're saving $99 by not getting emissions reduction tech.
Scenario 2) Say everyone else gets the emission reduction tech. Now, if you do spend the $100 yourself, then your premiums become $5000, but if you don't your premium only goes up to $5001. Again, it's not worth spending the money, so you stop doing it.
Scenario 3) Say exactly 50% of people have the emission-reduction tech. Then you can either get or not get the tech yourself, and the $100 will make the difference between premiums of $7500 or $7501. Again, everyone does the math, and decides that the reduction tech isn't worth it.
So, game theory shows that there can be paradoxical outcomes. In the scenario above, everyone choosing to spend $100 saves $5000 each a 50:1 gain, yet any one person choosing to spend the $100 only sees a benefit of $1, a 100:1 loss.
You can also see this as a variant of "tragedy of the commons". Say for example we shared a house and decided to split the electricity bill. I've worked out that I can spend $1 on electricity and generate $0.60 worth of bitcoin. Since you're paying half my bill, i decide that's a good idea (i am an asshole in other words). You then escalate by also setting up a mining rig too, offloading half your costs onto me. We keep escalating in this fashion, as whenever you do the math "will *I* benefit from adding 1 more mining rig" always turns up a "yes" answer. It's not about their being too small payoffs, it's that doing the dumb thing is always profitable for the individual, but it fucks it over for everyone else, and everyone chooses the profitable option, because that's the most "rational" from a self-interest point of view. So, these kinds of problems don't go away until you fundamentally change the perspective and decision-making process.