I think hes convinced this will help him have a legacy. His first term was a disaster. Trump and MAGA like to say things were great but he oversaw an economic disaster and a public health crisis that lead to millions of unnecessary excess deaths. This time, Trump wants to expand the United States. He thinks if he adds territory, no matter what else happens, hell be remembered for that above all else. He also doesnt understand the point of having a strong military if its not going to be used. He wants to be an invader. He wants to use nukes. And worst of all he wants to do this to people he considers weak. He will never talk to Putin or Winnie the Pooh the way he talks to our allies, not ever because he fears them and would fold like a lawn chair in a confrontation with them. But he will gleefully bully whoever he thinks he can get away with.