The Elon Musk style private founder is not really a new thing. Plenty of companies have been started & run privately, and in Elon's case there is a strong argument for that- it gives the founder more control of the company which can be necessary for the success of a risky business.

Dell's privatizations comes to mind. It was taken private temporarily, not to hoard all the gains, but to allow a single stakeholder to call all the shots and attempt a turnaround. Now it's going public again.