How Worried Should We Be About Trump?

I was talking to a colleague about this today.
I mean, what's the answer???
I oscillate between (a) Trump might actually destroy the world and (b) Ha ha! It'll probably be alright...right?
I think I've just knuckled under to the prevailing (b)-ish attitude.
Sure, he seems fully capable of bringing total disaster down upon us...but...y'know...I kinda feel like it won't happen...
But what the hell can we do? The recount is unlikely to help. The Electoral College is unlikely to bail us out. Impeachment seems like a real possibility...but that's unlikely to happen for awhile.