No, it stays in your project because you don't have to rip apart your previous work to salvage the expensive magic bit for the next great idea. You start building different kinds of projects because you know this and create many more awesome things that continue to make your life better after they are done.

The parts of projects that were left behind after pulling your expensive SBC are no longer junked so waste comes out a wash. In any case, a few makers experimenting in any fashion isn't even a rounding error compared to the mobile phone apocalypse thats hitting landfills now.