The same HN that is heavily moderated by a paid employee and paid for by a multi-billion dollars net worth company called YCombinator?
That's not the question. Hacker News was used as an example of an old-school site that worked without monetisation. Which is clearly not the case.
Do you believe that users are going to pay to get access to HN?
The only reason HN still persists at the scale that it does is precisely because of its association with YC and "tech bros," because the billion dollar venture capital firm running it has made it a part of their identity.
I suppose you could call the Launch HN threads ads, but only just, and they're of the absolute least objectionable sort—on topic, clearly labeled, unobtrusive, first party, with no tracking.