People who populate subs that only exist to mock, complain about, or troll other subs (or other online communities) that have little to no relevance in real life obviously have a lot of issues. They're clearly not very happy with their lives, so they need others to look down on to feel better about themselves.
The same is true for communities obsessed with "lolcows". These are mostly people very close to the bottom of society, so they find the 1 percent of people who are even lower on the social ladder than they are because they need somebody to look at and tell themselves "at least I'm not him". The more malicious ones that dox and harass lolcows are usually the angry loser types that got bullied a lot in real life and since they can't get revenge on those that bullied them in high school, they see lolcows as an opportunity to be on the other end of it.
The people in these communities usually don't admit this outright, but at times they allude to it. And at other times you can read between the lines.
The fact is, nobody remotely satisfied with their lives would be a part of those communities.