I'm curious to read about products that have failed to get longterm paying users, but that the creator still uses / derives value from. I think it would be an interesting list!
https://trombone.io/ - Meteor JS basically died when I released this and I never got around to making it technically stable enough for end users to want to pay for. I still use it for Meteor apps I currently run and it's really helpful.
https://tab.bz - Lots of users but I haven't figured out the right way to monetize, again I use it a lot
https://idbloc.co - TBC (just launched), I use it a lot and I think a lot of others will as I improve my reach and messaging
I've got a couple: