Why we can't avoid some of them is just because how far we're already gone. With global warming, with topsoil, with groundwater and water, damming etc etc.
The observational result is that atoms do not selfdestruct by the electrons crashing into the nuclei. What more evidence do you need, beyond the existence of stuff?
One reason for why some people still think it might work is that they envision a peaceful future, in where we cooperate with each other, backing off, slowing down, letting nature heal itself. Eco and biodiversity given a chance. That's a long game as it is about natures time scales firstly, ours secondly.