There was time 12 years ago when I stood on a turning point. I could have been an IT professional, a windows developer or a web developer in a mostly non windows environment. I choose the latter and never looked back.
Web development then became later mobile web and soon enough native iOS. In a nutshell that's how I became an iOS dev.
Similar story I'm sure for lots of other android and iOS developers. I must say say being an iOS dev is incredibly rewarding, the platform moves forward constantly, hard to keep up actually. Don't think I've ever been bored