I think he's point is that there are also disadvantages of growing up under high income (of course it depends on parenting too). Too spoiled, cannot relate to ordinary people, etc.

I seem to remember that many entrepreneurs are born to upper middle class parents.

Not spoiled enough that they cannot work, but still fortunate to have a safe upbringing and be risk tolerant.

(I do agree with you that people are born with very different prospects depending (among other things) on parents social-economic status)