Does that make his journey any less valid?

For himself? No.

But, a lot of this advice like “take risks” is much easier to do when your failures don’t result in losing everything. If a poor person starts a business and fails they might not be able to afford to eat. If Sam Altman failed would he have been pushed to a similar place on the socioeconomic ladder? My guess is no. It’s much easier to fail when your failure state is that you can rely on your well off family with relatively little hardship.

I don't think anyone is suggesting to start tech startups directly from poverty. Once you are in tech it doesn't really matter what your parents make; you can save enough from the generous paycheck at your corporate job to buy a laptop and pay the rent for a while. When your startup fails, you go get one of those again.

See Bill Gates.

No, it's great. I hope to help my kids start on the same rung, but I think I'll caution them against giving advice about "having enough money so that you don’t stress about paying rent," something a person who started in that income bracket has never once had to meaningfully worry about, obviously.