Elon Musk bet everything on SpaceX and Tesla.
After selling PayPal, he could have lived comfortably for the rest of his life. Instead, he put almost all his money into SpaceX, Tesla, and SolarCity.
The bet nearly failed. Costs were much higher than expected, both SpaceX and Tesla struggled, and Musk eventually had to borrow money just to cover personal expenses.
What motivated him was not another internet company. He believed industries like space, energy, and transportation needed new players because that is where major innovation was missing.
His view was that progress often comes from new entrants willing to take risks in areas where most people think failure is too likely.