I agree with @sparechange. If the size of the market is $1m/year and you have 90% of the market, you could do quite well for yourself if your margins are in order.
I know of someone that does Point of Sale for a particular retail store niche. He has something like 600 customers for his POS system. I don't know his profit numbers, but do know that he employs two $150k/year developers and seems to be doing quite well financially. The total market for POS for this particular type of store can't be more than a few million a year in the US. But, that doesn't matter. This guy is making more than most of the people on this forum.
I know of someone that does Point of Sale for a particular retail store niche. He has something like 600 customers for his POS system. I don't know his profit numbers, but do know that he employs two $150k/year developers and seems to be doing quite well financially. The total market for POS for this particular type of store can't be more than a few million a year in the US. But, that doesn't matter. This guy is making more than most of the people on this forum.