Why not charge 5000 users money instead of servicing 2M users for free?

It seems to me if you can’t get 1 in 500 of your users to give you $10 per year then maybe your product isn’t actually valuable or useful and should just shut down.

I say this without knowing anything whatsoever about this product or its utility; it just seems like a general thing. If you have this many signups and you can’t charge even a tiny tiny fraction of them, it means the signup number is irrelevant.