I don't know if there's a single "HN mentality". This site is an ongoing uneasy truce between the entrepreneurs (who have more of the attitude the GP is complaining about) and the developers (who tend to be more cynical about these things and, if they care about startups at all instead of working a 9-to-5, are more likely to have the "scratch your own itch" mentality). There's a lot of back-and-forth between which viewpoint is ascendant in the comments, usually depending on how badly-behaved SV companies have been recently.