I wouldn't say this for his staff. They tell them these are stupid and petty fights. But he goes to a Trump property, grabs a diet coke, a big mac, his cell phone and starts talking to his friends who encourage him to do it and he does.
This is in his nature and likely how he's done things his entire life. Becoming president wasn't going to make him more rational nor develop a long game.
He's out here looking like Jose Mourihno,
oh and what did michelle obama say during the 2016 campaign season: being president doesn't change who you are, it reveals who you are.