Possibly not the best example, since he was largely raised in his formative years by his white bank-VP grandmother while he was attending the top private school in the most diverse state in the country.
My father was homeless for a while while he was a child, and he had to drop out of high school to support his mother and younger siblings. My sister and I, meanwhile, grew up to be (respectively) a federal prosecutor and a university professor, both comfortably middle-class. This was possible thanks to the availability of good public education…not so much in the South Bronx where my father grew up, but in the neighborhoods he was able to stretch into by the time we were born, and in the ability of education to translate into good jobs. Some of these engines of upward mobility have deteriorated in the past generation, and there is strong pressure (eg from the probable incoming Education Secretary) to weaken them further. (The ability of people from some ethnic groups to move into the best school district they could afford has been a problem for a long time, of course.)
This might be a little self-serving, but I think it makes more sense to focus one’s ire on those who are attacking the things that make upward mobility possible, and on those who refuse to acknowledge the role society had in providing them a comfortable life, and not give Bill Gates a hard time because his father managed to provide him a nice middle-class upbringing, especially since both Gates and his father pretty clearly acknowledge the source of their wealth and support policy which would transfer a respectable share of that wealth into the mobility engine.
