There's a lot of people that are desperate for attention and validation and the karma system becomes really addictive to them.
I had a lot of contentious exchanges with one person, supposedly a lady, that had to insert herself in every conversation in the sub, screech wildly about anything that went against her progressive ideas, even if it was inoffensive, instigate dumb debates and then accuse people of creating strawmen or sealioning, and somehow found a way to pretend to be a victim every single time. If a post mentioned the holocaust - her husband's father is a holocaust survivor. If someone mentioned sexual abuse, she was a victim of rape. If there was a mention of a kidnapping, she was kidnapped at 16. If someone discussed a murder, her best friend was brutally murdered before her eyes, etc. It got ridiculous when some medical subject came up and then apparently she's a doctor with 20 years of experience in exactly that subject and who teaches on that subject at a prestigious medical school. I have no idea how such a doctor can spend 20 hours a day on reddit and get 120k posts in a few years, but maybe that's just me. And I'm pretty sure she had several alts because her comments would be immediately upvoted and any dissenting viewpoint downvoted to oblivion. A few of the posters also had the exact same writing style and used the same arguments, which of course they justified as "great minds think alike" and "that's because you're wrong, bigot". If she was ever genuinely downvoted, she'd immediately complain.
It really sucked the life out of the sub. And there are tons of people just like her on many subs.