I don't think any of them started one company with the thought that it was just a stepping stone to another one. Rather, they are passionate entrepreneurs who see opportunities and try to capitalize on them, believing deeply in each one. That they had the money for some of those was often good timing, because as with Richard Bransom and Mark Cuban, especially, they had other ideas or opportunities where the timing (and the associated funding) wasn't so fortunate that either never succeeded or never saw the light of day.
Bottom line, though, in my comment above is the word passionate. If you're not about your dream don't do it!! And if you're doing it to make your life's fortune, wrong objective. That might be desired and even an achievable outcome, but if it's the critical objective... without passion, no shot! And even with it, timing has to be perfect.