Well, I was into that rock climbing, and, alpinism, ski touring, diving, paragliding, various expeditions and god knows what else.
It can fill up your life, and if you have good close friends it may be enough to feel long term OK and have amazing moments, which I kinda was. In fact, I've spent all my 30s like that, and backpacking around the world. I needed that, I felt I needed that back then, and when looking in retrospect it was right emotion, it made me a more complete human being (and later better parent too). Some can get there without, I couldn't, didn't have the right environment for it when growing up. This worked very well even when married, my wife complements me well in this (we met on a climbing session so that part was covered).
And then kids came, one just before covid and one during. I clinged to that climbing (with buddy) a bit, that was my escape for few hours a week into easy good times that were. Then I had this year injury of wrist, and then broken foot (all in civil setting, ie falling down the stairs in kindergarten) and I lost it all, and I blamed kids internally. I was depressed a bit. My sleep for past year was never, ever uninterrupted, good 8 hours (those damned teeth, how could evolution fucked up so badly? any animal with this trait would simply die out over few generations). That normal sleep is just gone, and I am mentally at maybe 70% at better days, more irritable, less patient.
But the thing is, kids bring up the hardest moments just as much as the best moments of your life. And we humans generally are OK with suffering quite a bit for those few nice moments. Kids bring tons of those. Even when walking relative valley of the shadow now with small kids (diapers, various naps during day that block anything bigger, teeth and lack of sleep), without cheaping out and outsourcing many troubles to nanny (or grandparents), they are amazing to watch, to experience. They love you back, unconditionally (for now), and it just feels natural to continue what all generations since ever did. It had been a rough year, few folks died in close family, and when my grandpa died 2 days ago, hugging my kids made it much much much more bearable.
I am pretty darn sure that skipping kids would be by far the biggest regret of my life later, met quite a few older folks like that. No need to always do the mistake to realize others were right again. But - if one has some serious mental issue which make them unable to be a stable partner and caretaker, then it should definitely be avoided. Too many sad stories out there already.