Legally no - a nonprofit has its stated goals apart from whomever runs it, and if the managers aren't following those goals, they can be prosecuted. In practice

Legally no - a nonprofit has its stated goals apart from whomever runs it, and if the managers aren't following those goals, they can be prosecuted. In practice, small charities can get away with misusing their funds as long as no one notices. But a large charity like the Gates Foundation has a lot of eyes on it, so Gates really has sacrificed a lot of control over that money by donating it.