Elon Musk is a genius, one I admire for many reasons.
PayPal was revolutionary, and it gave him the money to start his other projects.
SpaceX was his bid to privatise the space industry. It, sadly, hasn't worked as intended, but the main plan was, I believe, to speed up innovation towards space through competition.
Tesla is a huge success towards more electric cars. Soon, Tesla will be able to approach other companies and offer to licence them their proven drivetrain, and they won't even have to make cars anymore.
He's done a load, often investing everything he had into his work, and it has paid off.