They're right. You must have built that thing for some reason. If you really need the money that is one thing, but if not then shelf it for a while. You will probably go back to it later on and modify it somehow for another project. That is the cool thing about getting into this hobby. you can invest money into a project and sell it at any time and probably get a good chunk of your money back. The way I look at it these builds give us something constructive to do that keep us from getting into trouble doing something else less favorable. I do see some guys out there on the fence wanting to purchase upgrades for their R/C gear, and having to give up something less productive like smoking, or drugs to fund thier builds. What a trade off.
Take some neighborhood kid or nephew out and teach them how to run R/C with it. Share your toys with those less fortunate and fulfill some kids dream.