As someone that specialized in Palm OS programming for a few years, I concur that there is a risk in picking the wrong specialty. But I did learn a lot in my days as a Palm OS dev. I earned the right to design and implement some really interesting solutions. I got to solve hard problems. I wouldn't have had those chances if I hadn't proven myself to be very good at what I was doing. On the other hand, my vast knowledge of the API of an obsolete OS isn't helping me much these days. I actually keep a copy of one of my Palm OS books as a reminder to never get to tied to one technology.