No man is an island - billionaires started from family. Success breeds success. Their parents were successful before billion dollar mark were reached. But it's not a sign that you should stop trying
Jeff Bezos
His parens gave him 300 000$ - it's 505 000$ in today currency. You know, it reminds me case with Trump - his father gave him 1 000 000$ and some respect, because he is a son of respected man. My parens even if they sell everything that they have and some internal organs they would make only 100 000$, Jeff got 5 times more.
Imagine that Jeff didn't invest all those money in to business, and he bought a home in tropical paradise - He would be happy in any case.
Bill Gates
He was born rich. His mother helped him to get foot in the IBM's door . Gates didn't creat Microsoft OS - he bought CP/M clone and changed name of this operational system to MS - DOS. Everything else is only history. He won competition with CP/M because hiw OS was cheaper. His best competitive advantage was his family, not brain.
Carlos Slim
When he was 10 years old his father had a business and property. Carlos only continue father's path, he invested wisely money that his father earned. He is role model for rich kids, not fore average like I am. There is stages of developmen, because his fathere he went through those stages fast, alot faster than 99.99% of people.