It's fairly well-known that some accounts "karma farm" by posting comment designed to be upvoted, and then use the credibility to sell themselves to marketers. Also, I believe it's fairly straightforward to buy votes in your posts from sock puppet farms.
Here's an old post from a security researcher that wrote papers on this topic, and also experimented with buying votes:
If you moderate large enough subs you see this just often enough. They'll find another sub to farm karma on, then come to yours to spam their random new domain. I wish reddit automod could check the age of the domain since it was registered, could help, although it could also be straining on reddits part, but I've seen some weirdo who gets a new domain and spams blogspam thats just ripped off articles with ads all over. I'm surprised they're turning a profit wasting money on so many domains.
Before ever being a submod anywhere, I had no idea of half of what goes on in reddit.
This person drives in a small car in other drivers' blind spots, waits for them to try to merge in front of them, then uses a novelty car horn.
Then they upload the video, which Reddit loves because it is watching someone else possibly make an error thereby making the viewer feel better about themselves, and then they get an opportunity to share a link for the horn in the comments when people (or maybe the original poster’s alternative accounts) inevitably ask where they can also get a horn like it:
I do not see what other explanation there could be for why a person is recording and uploading so many incidents of the same type within such a short timespan.
That sort of incident happens every day in the Bay Area, but people just yield or pre-emptively make room when they see the other guy is going to do this. This guy has decided not to and so he's got a lot of videos. That's literally it. If you decided to hardball every driver interaction you'd have enough of this content too.
Here's an old post from a security researcher that wrote papers on this topic, and also experimented with buying votes:
https://www.reddit.com/r/netsec/comments/38wl43/we_used_sock...
I am unsure what the current field is like.