https://news.ycombinator.com/item?id=19712057#
Always wondered this. Sometimes I feel the need to do something else outside my field, and possibly get some money out of it.
A lot of my other hobbies are not money makers but at least money savers. I have a garden, hunt, brew my own beer, make my own wine, and perform all sorts of home repair.
I make beer money at most, nothing ground breaking but its fun to ride a bike, tell people about the history in my city and meet fun people.