I ran a free system and while it is small it easy but as soon as you get tens of thousands of users you are on the hook for all of the background costs while your userbase grows exponentially because they are so happy. Better to have 10 customers then 10,000 free users. I was never able to get free people to pay anything. I bragged about my free users and I felt self-important while taking away my ability to use my time more wisely.

I've noticed online services which probably cost a few cents per user to run seem to either charge $0 or something like $10/month which works out quite a lot. I wonder if there is a gap for charging say 3x actual costs which might be say $5/year or $10 for 5 years or some such?