There's a lot of terrible software on the app store, median revenue is a poor indicator of the market's success. Most restaurants fail, but that's not to say restaurants aren't a good business. Some are just a lot better than others.

I'm not saying it's easy. I'm just responding to the question posed by the article. There are quite a few app store millionaires. But like most tech markets, there are a few players that take the lion's share of the profits.