With a front page that has daily "Omg facebook is sharing your data", "you'll never guess what uber did now", "<random shit tech company> S-1", "let's all play armchair detectives and speculate why the 737 crashed", "shitcoin is good/bad for <whatever>", etc posts, I wouldn't exactly put HN that much above crappy content aggregator..
There are ads. The "<who cares> is hiring" ads, and I wouldn't be surprised if some content here that goes straight to the top isn't paid for somehow.. There's a large audience here, and no transparency in how the site operates, so the incentive is high.