The sad fact is that limiting guns will not limit the ability of crazies to kill people. They'll still manage to figure something out. At one point it was bombs, then planes, now it's trucks, even knives have been effective terror weapons in Europe. At what point does it end?
Tyranny is as valid an excuse as any, so I'm not going to argue against anyone that wants to keep a gun for that reason. But personally, I've found more use on the personal protection side of things.
It's not the government having too much power that scares me all that much (although the fear is there), it's the government disappearing completely and leaving a vacuum. I've lived through that. Hurricane left us without power for over two weeks(Not nearly as bad as Puerto Rico, mind you), no method of communication for 4 days(I got my ham radio license after that, for other reasons, but it's still nice peace of mind), roads blocked for nearly a week so we were unable to make it even to the closest emergency shelter if we'd needed to except through a 8 mile trek on foot through questionable and dangerous terrain. There were literal pirates floating up inland waterways on boats and robbing houses. Those are the situations I'm truly glad to have a gun at home, because sometimes the government isn't there. Sometimes there is no help. Sometimes you're on your own and there are bad actors out there who will take advantage of it.
As for fixing the problem. You'll likely never solve the crazy lone actor problem. But the bigger problem is whatever is pushing people to feel desperate enough they need to use a gun. I keep hearing mental health come up, and that needs to be worked on, but simple welfare safety net improvement. UBI is probably the most notable call for something like that recently. But take away the threat that people will lose their basic survival necessities of food, shelter, medicine, etc, and you take away a large chunk of the incentive to do harm to others or to themselves.