A very large percentage of those people are former FAANG employees, employees of companies trying to get acquired by FAANG, or employees of companies doing exactly the same things that FAANG are getting criticized for. (Some are all three!)
I doubt any of them are getting paid to AstroTurf, but they know what side their bread is getting buttered on.
Quite un-so! HN is targeted at one group only: the intellectually curious. So curiosity—keeping HN interesting—is the only thing we care about and optimize for.
As for VC-funded startups, since only about 10% of HN users are located in Silicon Valley, the number working for such startups is certainly far less than that. 50% of HN users are outside the US. This community is orders of magnitude more diverse than your image of it here.
People work for many different employers. Are their views impacted by their work experience? Of course they are—for every user here. There's nothing sinister about that. If someone posts a view that's wrong, others will correct it. As long as they do so thoughtfully, that's great. The cycle of life on HN.
Is it 50% of registered users or 50% of active commentators? And I think the image HN has been trying to cultivate is vastly different from the image of what HN actually is, at least from some of the other sites and circles I post on. The rather negative reaction to the Katie Bouman news as well as the summer programming for women incident show that somewhere down the line there is a serious breakdown in what culture HN is trying to create.