I think what OP means is rather than trying to fix deceases one by one, why aren't we focusing more on the root cause (aging)? This seems like a much more efficient way of solving many of these things. There are a bunch of initiatives in this area already, but not nearly enough to be proportional to the potential.

> but you can't just spend a trillion dollars and make people live an extra decade.

This I don't get though. Why not? We already do that. Making people healthier for longer is a massive win.