I didn't say wealth, I said success. That means different things for different people, right? I think that people should at least get themselves established before taking on a lot of debt and responsibilities before they have had a chance to live a little. What's wrong with that?
A number of things - first, your health & fertility fade with age. Second, this is doubly true for women. Third, who wants to be a 60-year-old dad with a teenage kid? Fourth, youthful parents recover from injury faster. Fifth, young parents can keep up with their kids. Sixth, is is better to be involved with the kids, or to be able to "provide everything"?
My advice (worth what you paid for it...) - have kids in your twenties, or don't have kids.