And honestly, if what you want is to make money, be a dentist.
And if all you want is to build something just for the fun of it, don't start a company. You'll lose money, time and nerves. There really are only to options when building something. Either build something people want (and if somebody built it before you did, build a better version - see: Altavista, Yahoo and others vs. Google) or build something, and then make people want it (see: iPad).
But don't start a company to build something just so you can satisfy your professional curiosity. That's what side projects are for.
The web was a side project. It changed the world. Linux was a side project. It also changed everything. Angry Birds was a side pro... wait, no it was a way to make money... and that's fine. I'm not trying to say, "Don't make money." I'm saying, making what people want gets you Angry Birds. Making what people need gets you the web.
So your point is that you should build something that you believe people will need even though this need/want doesn't yet exist. Ok, I can agree with that. But if you're going to run a company, you better build something people want now, or be able to make people want it, otherwise you'll go bankrupt.
And if all you want is to build something just for the fun of it, don't start a company. You'll lose money, time and nerves. There really are only to options when building something. Either build something people want (and if somebody built it before you did, build a better version - see: Altavista, Yahoo and others vs. Google) or build something, and then make people want it (see: iPad). But don't start a company to build something just so you can satisfy your professional curiosity. That's what side projects are for.