I do agree it is tiring.

I can honestly say I can run every single one of my cars. I'm just too lazy to swap out electronics I do properly maintain the cars I race with and semi-maintain the ones I bash with.
If the car is discontinued/really old, I just shelf it. I don't wanna risk breaking it and spend countless hours trying to find that part. Yes I could sell it and try to salvage a very small percentage of the money I've spent on it, but I don't see the point in doing it. It makes for a nice display as an on going collection. Of course when non RCers see it, the inevitable question pops up "How much did you spend on RCs?"