I mentioned to someone that in my spare time I made iPhone games. They asked, "as a hobby or you trying to make money?" I replied that sure, I'd like to make a few bucks. He said to me "If you let your hobby become your job, what will you do for a hobby then?"
At that point, I realized that making a distinction between a hobby and a career path is a good move, and you have to know what you are pursuing. For example, I tinker with arduino in my spare time, as a hobby, and I don't intend to sell or make money off anything I make with arduino. There is nothing wrong in learning, say, Ruby in your spare time because you know that it will come in handy and that you could make money with it. But that's not a hobby.
Doing iPhone development (among other things) is my full-time job, and I am loving it -- mobile app dev was never my hobby, but a career choice, and I'm ok with that because I am happy at the place I work.
I get it, you should be free to enjoy your hobby without money clouding your thinking. Totally agree with that.
On the other hand, I think a hobby that could be something more is totally legit. For instance, I am learning Haskell as a hobby. I'm not really sold on it as a great language for business (yet), but I realize that if I get good enough at it I may be able to shift my career in that direction.
To answer the original question you were asked: If that happens I'll get a new hobby.
I think the real point of "what are you going to do for a hobby" isn't the fact that you can get a new hobby. The point is, you like your hobby (you find it relaxing and stimulating at the same time). When you make it a job, it ruins that experience. So back on point, if you're programming as a hobby -- great! But if you're constantly looking at the screen just to get ahead... that can't be healthy.
I just tell people I have a great job because I'm basically being paid for doing my hobby (web development). Been doing that for ~15 years now and I've still haven't felt any diminished desire for my "hobby", despite it now being my "job".
There are days of frustration, sure - but those pertain more to the business aspects of "monetizing" this hobby (such as dealing with clients when doing contract work), than to the art & craft of the hobby itself.
I don't think a hobby necessarily has to be less enjoyable just because you've made it your job.
"I don't think a hobby necessarily has to be less enjoyable just because you've made it your job."
This may be true in some rare exceptions. However, hobbies have no deadlines, no schedules, no management, no commute (ok, maybe not if your hobby is somewhere else), no feeling of "I have to do this", etc. All these reasons take away from the pleasure of doing your hobby, add to your stress -- which is the whole point of having a hobby in the first place, to take your mind off of stress of daily life.
I have hobbies outside of my "job" too, and perhaps sadistically, I give myself schedules & deadlines there too. I feel that if I do this, I can keep myself on track and even record my progress to a certain degree. I tend to get great satisfaction in a completed project, hobby or job. And I find the pressure of a deadline gives me this strange "high" - kind of like a runner's high - right before I hit my deadline and/or complete the project.
I totally hear you though. I can certainly understand how such pressure can totally take the joy out of a hobby for most people. And I never try to force anyone on my teams to think or behave this way, unless they naturally do already.
At that point, I realized that making a distinction between a hobby and a career path is a good move, and you have to know what you are pursuing. For example, I tinker with arduino in my spare time, as a hobby, and I don't intend to sell or make money off anything I make with arduino. There is nothing wrong in learning, say, Ruby in your spare time because you know that it will come in handy and that you could make money with it. But that's not a hobby.
Doing iPhone development (among other things) is my full-time job, and I am loving it -- mobile app dev was never my hobby, but a career choice, and I'm ok with that because I am happy at the place I work.