The key risk when turning hobbies into a business is that the core focus area of the hobbyist's expertise will likely have to shift dramatically, and it's often that shift that may cause a loss in enjoyment and fulfillment.

A hobbyists can focus on extremely uneconomical aspects of a thing, precisely because they don't need to think economically about it - a business person doing so will likely fail at both their business, and tragically, their hobby...

For anyone interested in a deeper exploration of this theme, I will shamelessly plug my podcast on deep, obsessive hobbies, "When The Work is Done": https://www.whentheworkisdone.com/

Only managed to put up one episode yet (an interview with a very successful neuroscientists who spends almost all his spare time tailoring...), but am hoping to have many more episodes in the works soon.