I think there are three kinds of desktop app developers that make real money today:

* People who make huge profits fast, because they built a desktop client for popular webservices (see terhechte and his InstaDesk)

* People creating good software for niches that REALLY NEED that piece of software to get work done.

* Companies building large software suits for big companies that spend huge amounts of money in licences and support.

I personally think everyone in the middle is also doing well, but not enough to make a living out of it.