Trump has already caused decades of harm, some probably permanent. When people warned of irrevocable damage should Trump be elected, this is what they referred to.

A single example: Iran. If they still exist when Trump leaves office or dies, they're not going to jump back into the Iran Nuclear Deal. If we don't want them to have nuclear weapons, Trump shouldn't have withdrew us from the agreement that was working in 2018 just because it was an Obama success! Shit like that is why we're fucked...