I can loose interest in HN in about 15 cumulative min / day.

And I often got some valuable tools/libs out of it.

Reddit is infinite, as well as much other social media

Turn on noprocrast in your account

True, but compared to Twitter or reading about Ukraine, HN doesn't make me angry or depressed.

hn is a lot slower. Sites like reddit, twitter. They practically show you a whole new page every time you visit.

It's pretty different. Compare the BBC, for example, where basically every article on the front page seems to subtly or not-so-subtly imply that our planet is on the brink of full-blown catastrophe. While such articles occasionally gain traction here, it's mostly just cool tech news and interesting stories. Perhaps not as engaging, but much better for a person's mental well-being.

Not untrue, but it's one of the less bad places to come on the web.

It can also be to do with your own mental filter... HN has submissions that are both on the pessimistic doomsday side at one end and hyper over optimistic side at the other end, but orthogonally there are also purely fun submissions - and these can be quite uplifting, a happy reminder to many of us of why we originally ended up doing what we do.