My best Reddit experiences were where Reddit facilitated meeting people "IRL". I found my first D&D group on Reddit, made 3 great penpal friends, scored a couple dates, ..., and one romantic relationship.
I really don't know my worst... A couple times I let people get under my skin, but I eventually got good at blocking people.
I assumed OP would be willing to say it it was "just" that. This being the Internet and all, people admit to way weirder stuff all the time.
When I was a Boy Scout, we often had kids who would refuse to go. It was a whole thing that we had to check on. (Along with asking everyone how yellow their pee was.)
I remember one guy was in tears on the hike out, and it turned out that he had faked out the scoutmaster by taking a walk with the TP and shovel, but not actually gone. Poor kid was barely able to walk, but kept insisting he couldn't void either.
I only learned later how serious it can get if prolonged.