[*If not in the USA, read "Old geezer". Credit: Aachen]
Many varieties of "I really regret that I [did|didn't] do X when I was younger" occur in older humans.
The stereotype of young men wanting to avoid all the work and commitment of setting down, marrying, and raising children is older than the pyramids. It is obviously not true of all young men, but there's very seldom been a shortage. Sure, their feelings may change as they grow older - but a young man whose main motive for marriage is "so I don't regret not having kids when I'm old" strikes me as a young man who the young women should avoid.
In some cases, I get the sense that "I really regret not having children" is mostly a way of articulating "I am old and socially disconnected and feel lonely and depressed". In the modern world - where kids generally grow up and move far away for jobs - having had children would probably not help much with that.