Respectfully, I think YCombinator is well aware that the benefit to them is greater than the cost of running Hacker News. In addition to Hacker News making the

Respectfully, I think YCombinator is well aware that the benefit to them is greater than the cost of running Hacker News. In addition to Hacker News making them the most well known startup accelerator in the world, who people will apply to from all over the world, it also provides benefits for their incubees, as they get free advertising on Hacker News, and presumably this makes their investments more likely to succeed (although I'd love to see a comparison of the historic portfolios of various startup accelerators)