I don't think Trump has actually ran his company in a very long time. He is a failed businessman several times over. I believe the actual running of the company was taken away from him a long time ago and he is merely the spokesman. He claims to have a "real estate" empire but he doesn't actually own much. He just lends his name to the buildings because people are fooled into thinking his name is synonymous with luxury.
That being said, your point remains. He is in a position to enrich himself although it's not that different from what Congress does. They routinely engage in insider trading which isn't illegal in Congress. They all leave Congress as millionaires.