I've always thought the best way to kill a hobby was to turn it into a job.

100%

I tried turning my hobby of programming into my job. On the surface, I was reasonably successful, but the most enjoyable aspects of my hobby had to be set aside in favour of actual productivity.

Worse, the fact that I actually got pleasure from my work left me open to exploitation. When I finally woke up to that, I ditched programming in favour of "just a job" that paid the bills and was about a million times happier as a result. It's only recently, 15 years after leaving the field, that I find myself once again drawn back to programming.