I sell programming ebooks. Started in late 2018, the last two years have brought in more than double my needs. Which is just about $150/month (I'm from a developing nation, live alone in the outskirts of a second-tier city).

Compared to what I used to earn 8 years back, the current income is only about 30% (not adjusted for what I might be earning now). This is still more than enough and I'm grateful that I don't have to look for a job.