https://www.youtube.com/watch?v=irsF1W3StWk
It is called Risk Homeostasis, it is when you do something risky but do not experience the negatives. It is like driving through red traffic lights, if you do it 10 times and you do not have a crash then you start to think that you can ignore red lights. The risks and dangers are still there but you have just been lucky, until you aren't.
Trump has always had this mentality of, you can do awful things and get a lot of media attention but if it gets to hot then you can just back down. Iran is the one thing he cannot back down from and has no escape strategy. It is going to be the biggest of the black marks on Trumps legacy. Considering a lot of what he has done on the international stage, that is pretty damning.