We're talking about a guy who managed to run multiple casinos into the ground. Casinos. Businesses which at their core consists of people handing you money and you getting to keep between 25-50% of it on average.
On top of that, he was laundering gobs of money through them (the Taj Mahal for sure) and still couldn't manage to keep them afloat.
Running the Federal Government like it was part of the Trump Organization was one of the few promises he actually kept and boy does it show.