Would the people in the HN community stick around if HN started showing ads and selling their data? They could easily move to a similar site, such as lobste.rs.
Would people pay money to access HN? Much of the value of HN comes from the users who spend time sifting through a lot of junk articles and comments to upvote the tiny fraction of interesting ones. Are you going to ask users who create the site's content to pay for it?
If you can't monetize the site without driving its users away, then it's worth $0.