Painful and true. When we started up we thought we were going to sell some fantastic developer tools . . . then realized that there was no money in that. Then we developed a niche product that actually pays the bills.
If money is coming in at the end of the month you're on the right track, if not then you won't be around for long.
This makes me very interested to see what happens when my company (all two of us) has a shiny, new product to hit the road later this year.
Admittedly, we're scratching an itch, and very focused on the idea of 'getting money by making our customers really, really happy.', so the idea of 'changing the world' is really way down on the list. Even so, I'm expecting a very, very interesting ride. :)
If money is coming in at the end of the month you're on the right track, if not then you won't be around for long.