Maybe regret is too strong of a word

Just that if you could go back in time and do it over again you'd stay single

I doubt many will admit it because it would be admitting they might have given into societal expectations or didn't want to appear as a "loser" to others by still being a single guy in their 40's and beyond

But any willing to admit it wasn't exactly as hyped up as it was made out to be and you'd probably be just as happy (if not happier) as a single dude with none of the obligations/responsibilities that go with raising for a family?

They will never admit it. Oh, they'll talk about how annoying and life sapping their kids are or joke about how they had to sleep on the couch because they forgot to take out the trash, but after making all of those statements they always, without fail have to interject with; "but I love them and wouldn't change it for the world." I've heard that "disclaimer" so much, i'm starting to doubt the authenticity of it.

The British nobility stick them in boarding schools basically all year and have 'nannies' when they are at home. It's not unusual for them to forget their names, or even that they exist.

sometimes you can see the soul-sucking exhaustion in their face. Like you see them pushing a shopping cart in the food market and they just look so "life-tired"

looks brootal

Also children grow up to be terrorists, insufferable lefties, 'influencers', insurance salesman, politicians, TV presenters, etc, etc. Think what you are likely to be actually creating, and blow the money down the pub instead.