Yea that's an interesting topic.
To answer the question and share my personal experience : I started by doing a pixel character animation, I found it cool to do, and then I went like "why not make a video game with that ?" knowing that at this stage I was already aware of Construct 2 because my brother was using it. So I just asked him to teach me the basics, then I played around for quite a while but I was really enthusiastic, and I eventually brought everything together and made the game. I would say now I am so passionate about it that it is not quite only a hobby anymore, but more than that. I kind of expect that after several games and more experience I would be able to sell my games and make money out of it. Also my main motivation to make games is that I am working for myself and I don't have a boss. I don't think I would like to make pixel art animation for a boss who would pay me for that, that would be too close to my professional job.
I spend around 6 hours a day to do my professional job which is animating characters for cartoons (TVshow, advertising) and 3 hours a day working on my game if I don't hang out with friends in the evening. I'm very happy with that balance but I would rather do games all the time.
I think lots of people have different motivations that bring them to eventually make a video game. One example that truly fascinate me is Tarn Adams who is a genius programmer. He started a game that most of you probably already know called "Dwarf Fortress". We could say that for him it is definitely a hobby considering that he is not motivated by money at all. But now it became so big and people donations are big enough so that he can actually do that all the time, I would say the hobby turned into "professional art".
Notch even offered Tarn to give him a large amount of money so that he could hire a proper team to make his game. But Tarn refused explaining that it wasn't like that, it wasn't the purpose of what he was doing.
wmsgva I totally agree with what you're saying. Putting a good team together, even if you have money, is really really tricky. And if you don't have money, well... I think it's possible but very random. But I would add something more : Before coming up with ideas I think it's important to be very aware of what is done around in the indie game industry. Lots of famous indie developers are sharing their experiences on the internet and it is incredibly valuable knowledge. They also share their tips, their workflow sometime. Seeing what they do also let you know of the "trendiness" of what you do, or if your game is original or if there is actually already somebody who made a game that is like your idea. Being very active in communities is also something incredibly important as people can considerably feed your idea with other good ideas.