I realize that money isn't everything. And developing for iOS means more than that. I do think, however, that it's weighing on the minds of a lot of people picking a career path.
Building for iOS gives you the ability to reach millions of people that care about design, and experience. I feel like a mobile gives you the opportunity to reach people in a more personal and intimate way than a web app.
The fact is, there are as many reasons for choosing a platform (web, iOS, or Android) as there are developers. I'm actually very interested in hearing other developers reasons.