A hobby that makes money is a job, once you start to depend on it it starts being stressful and stops being a hobby. I've been through that cycle a couple of times.

Other hobbies can even make you money.

My hobby is data entry in spreadsheets for banks and oil companies.

I've completed sailing course recently, and I'm still in awe that one of activities that the instructors do in their spare time is handling the private yachts between ports, like bringing one from Greece to Spain. Seems like an awesome side gig.