I wasn't alive during the Cuban Missile Crisis. The one thing I strongly believe, from what I've read about it, was that Kennedy's restraint most likely saved the world from a nuclear war. And he stepped back and thought before he decided what to do - or more importantly, what NOT to do.
Imagine if Trump had been President during that time. The guy who can't let the slightest insult pass him by without "hitting back 10 times harder" and who tweets insults at heads of foreign states if he thinks they've slighted him.
Does this scare the crap out of you? It should.