It is natural after hi school for people to lose interest, though. We have to face it: for most people, calculators aren't a priority in their life.
Many calculator fans in the TI community in general are like ice hockey fans in Southern USA. To keep them interested in supporting teams you have to give them more reasons to do so, like during summer we had a programming contest with prizes. The established members also need to produce lot of interesting products. In southern hockey markets, teams have to win, else you get a Phoenix Coyotes situation. It even came to the point where someone on United-TI suggested that eventually, calculator programming groups would have to pay their staff to keep them active. Fortunately, the new innovations in calc programming in 2009 will probably be enough to keep more people interested for a while.
Because many community members aren't that loyal to the TI community (ie: their absence during Summer and their short stay in the community), most have higher interest only when they are in hi-school and have math classes. During summer, calc programming interest often goes down. When people start college, most of the time they no longer have math classes, so a graphic calculator is not needed anymore. This is when their interest slowly fades away.
That said, being more busy doesn't help either.