It's of course a very nice story that they "dropped out of school", but the truth is more nuanced than that. For example Bill Gates and Elon Musk had school as a backup plan in case their business would fail.

So it's not that they dropped out of school to pursue their business, they suspended their school for their business, and still had it as a backup plan. Very different! If their business wouldn't have worked, they would continue their school (which at that point was already an investment, 3 years for Bill Gates if I remember correctly).