You're forgetting a major one: there's a whole gulf of things that people just aren't willing to actually take their wallet out for. People even scoff paying $8/mo to Netflix while spending hours watching it daily. Good luck taking payments for your little project.
For all sorts of reasons, too: we have been conditioned to think ads = free, none of your competitors ask for money (they use ads, so they're "free"), the modern payment flow is still cumbersome and doesn't support microtransactions, there are all sorts of things like HN that I simply wouldn't use if it wasn't free, your users can't afford it, etc.
One of the worst aspects of ads is how they've mutated our society's relationship with paying for things that we value, but ads definitely fill the void outlined above. Your creation's value to society doesn't have to breach the high threshold of getting a user to take their wallet out.
But just think of all the things you have done on the internet today, all the things you enjoyed doing or thought were worth even a tiny amount of attention, yet how unwilling you'd be to actually send money their way in the current system.