I often see active authors on Hive who delegate 90%-100% of their HP and in my opinion make a mistake that is counterproductive for them in the medium to long term

I think some users who do these are mostly not active, so I think they probably do this to earn curation rewards while they're not active. Although I think it's important to at least leave 50% of your HP without delegating it out, this way, it's important to use it support others while building important interactions and friendships too.