I'm not sure about Trump as he shows less control and comprehension as time progresses, however, the "Oh Kim won't do anything" school of thought isn't something I am comfortable with either. Whatever his base mental state is, his entire upbringing was that he was a demigod, like his father. I have no faith without evidence. Killing family out of paranoia is not a good sign.
Nevertheless, once we commit to war the consequences are out of our control and Iraq is a perfect example but NK is even worse considering there is China and Russia in the mix. No, I don't think they would go to war with us but yes I do see this as an opportunity to tie us up in knots as they do in an eternal Grand Game. We need to avoid that.
The best I think we can do is ignore Kim openly but keep an eye on him. If he were to have an "accident" then those not impressed from birth with a sense of godhood would be the result and a better chance of peaceful resolution all around. Of course, covert action isn't automatically a good thing and I am uncomfortable with that from both a moral and practical perspective.
The bottom line is that of all bad choices a first strike is likely the worst, and "what iffing" ourselves into war is rarely wise.