If you look at the leader board (https://news.ycombinator.com/leaders), you'll find a few old accounts that pretty much do nothing but farm links, posting sometimes dozens of times a day, with a very low percentage of comments. Their high "score" isn't an indicator of quality; they just spam enough that a few get some good upvotes, but most of their submissions are low quality.
Each one gets 4-5 karma, a few crack double digits. Post 10 or 20 a day over a year or two and they're five figures. Pure farming.
..or are they selling the accounts?
They averaged 14 karma per post, but most of that (218) is in one NYT share that hit.
That's right on the norm for this account. The prior two weeks of spam had one hit in 26 (Guardian, 500+ karma). The prior two weeks of spam had one hit in 30 (London Review of Books, on the Iran war, 100+ points before getting flagged). The prior two weeks, one hit in 15 (Guardian, 81 points, a dupe of an earlier submission).