I gather Musk did. But I'd agree the argument that the easiest way to become a billionaire, at least in the tech industry, is to be born to exceptionally rich parents probably doesn't hold water. Still, I don't think any of them grew up dirt poor either.

Yes/No/Yes/No/Yes/No/No

"Mansions" is hard to quantify; whether a given house was a mansion will be subjective, and doesn't correlate super well with the amount of financial support they gave their child. But if you want to really dig into the details:

> Gates

His father was a high powered lawyer in Seattle; his mother was a member on a number of corporate and philanthropic boards, including one that gave her direct access to the Chairman of IBM at the precise moment that Microsoft was attempting to sell software to IBM.

> Bezos

His parents loaned him a quarter million dollars to start Amazon in the mid 90s.

> Ballmer

His father was a "manager" at Ford, which could mean a wide range of things; he grew up in a very wealthy area.

> Allen

He seems to have come from genuinely middle class roots - his parents were a librarian and an elementary school teacher.

> Musk

This one is pretty complicated; his father owned an emerald mine and seems to have been quite wealthy, though Elon disputes his father's claim that he invested money in Elon's first company.

> Page

Both parents were academics in computer science.

> Brin

Both parents were academics, immigrating from the USSR to the US - his father ended up teaching math at the University of Maryland, his mother doing research at NASA.

So that's two (Gates and Bezos) where their parents were significantly wealthy and influential in useful ways; two where it's unclear how much they got real benefit from their parents' wealth, but they certainly didn't grow up poor (Ballmer and Musk); two where the parents weren't rich but academically involved (Page and Brin); and one where they were genuinely just middle class folks (Allen).

I've got a friend who's sometimes used as an example of breaking out of impoverished surroundings. They note that he grew up in public housing in the burned out South Bronx Regan famously toured on TV, and after graduating Harvard Summa Cum Laude, went on to become a successful and well-known frontrunner in his field. He's smart as hell, a great guy, and add hard of a worker as any. So was his father, a construction worker who played an instrumental part in mentoring his son. That's the ideal, right?

He gets irritated as hell when people use him as a token success story because he knows none of it would have happened if he— among many others just like him— didn't win the lottery at an elite prep school close enough for him to logistically manage attending despite no family resources. The hard work, character, and intelligence were the base line that would likely have meant modest incremental gains— like his smart, capable, hardworking father made— without winning that hat draw. The connections he made in prep school— not even at Harvard— got him where he is in his career. When you're living on the edge of financial solubility, you just don't get the opportunity to invest in the future because 100% or more of your output goes into funding your present, and there are a hell of a lot more smart people out there than lottery spots in elite prep schools. The difficulties that his childhood friends faced progressing through public high school in that environment sink a lot of people with a lot of potential-- the graduation rate of his local high school is currently 26%, and how many of them do you think attend Harvard, where 46% of white students were admitted with the help of legacy status, proficiency in almost exclusively white sports not available in public schools like fencing, squash, and crew, or being the child of faculty? If you think people who get that start in life have equal opportunity to make something of themselves, you're delusional.