I must have finished like 15 projects that was meant to be generating money and was technically capable to do that.

Biggest failure was SAAS for organizing wineries and generating reports for carious government bodies. There are various old software from 90s that do that or you can use paper books (depending on country you are not allowed to use excel).

I've spent around 3 years of fulltime work but it turned out farmers do not care about software. They might use some old desktop software or just hope that inspection is not going to come. Software is still up and running and there are some paying customers, but it just doesn't make sense to spend much time working against the wind. Also my addressable market is not big enough to support additional development.