[encoderer]

Main lesson that seems to not have been learned yet, since it's not mentioned at the end:

If you want to make money (any money at all), stop focusing on consumer products, build a small B2B product instead.

[krater23]

And build it full time, not as a hobby. And build one that no one else is selling already.

[encoderer]

No quite the opposite! Part time is fine, and you can build a simple niched-down version of a popular tool.