He's how old now? At a certain point you become set in your ways and it's very hard to change. Trump views everything like a business. In the business world you want the company to succeed no matter what, and will do really anything to make sure it succeeds. When people actively try to sabotage that "business", like most people in the federal government are, he doesn't really get why and keeps cycling through them trying to find the couple that aren't.

He will never be able to understand that the way he's pushing isn't going to work. You don't keep using people that have been part of the government for decades just because you would do so in the business world. That's why he's going to get fucked over again and again and never see it coming. It's also why we need to keep pushing forward and not rely entirely on Trump for everything. He pushed the door open, now we need to keep going.