Musk didn't start with $100 million. He started his second round of start ups with the money made from the first ones. And he didn't have $100 million for the first round of start ups he founded.

In fact Musk has pretty much suffered through all the regular pain founders suffer through.

I remember watching somewhere on Youtube, during his first start up, they would code on a computer by the night and host the application for their users during the day on the same computer.