Yes, in my experience -- which includes observing others -- first world kids who have the luxury of setting high expectations for themselves tend to beat themselves up most when they are in the midst of discovering whether or not they can actually meet those expectations. They do that for a few years and then figure out how hard they're actually capable of working, and at what pace.

I think the self-abuse is just another way of describing what it's like to not know how to intelligently push yourself. You end up pushing yourself too hard before you establish a sustainable rhythm.

you are somewhere around 28-32 and currently feeling very confident/happy with your life navigation in relation to your earlier twenties?

I'm 33. I would call myself only moderately confident and happy, but that in itself is a major improvement on my 20s... when I was floundering around doing the above. I'm still getting better at it all the time. Around 28-29 I passed some kind of competency threshold and got slightly more competent than incompetent, with an attendant drop in pain from self-abuse.