What would I say? Just what I'd said; that searching for a "solution" that allows working 80 hour weeks + having a healthy family life is futile because, IMO, it doesn't exist.
At least when you have kids. I could see a spouse being okay with "5-10 years of hard work" for lots of freedom after that.
Hard to make that sacrifice with kids though, because after 5-10 years, they're basically not kids anymore.
Ironically, if the 5-10 years works out, and the kids have a guaranteed life of luxury because of it, they might be grateful.
But I don't think it usually works out that way.
(Note that I'm only focusing on the "80 hours/week" thing. If you can pull off "changing the world" (or at least your pocket book) on 40 hours/week, more power to you.)
So what would you say to the young [insert famous and wealthy figure here]?