When I started buying extra ML's for customs, there wasn't even a 6" SW line, so I never dreamed a Joe line could be a reality (and it still might not be). But it happened with everything. I bought a shit-ton of custom Joe parts from every castor in the known world, and every figure got made eventually. So I stopped that. Parts are still there.
Then I bought lots of spare TF revoltechs to make my own G1 cast, and a few figures in, some talented chinese guy with a 3D printer started pumping out his own, far better than anything I could produce. So I stopped that, tons of spare figures still there.
Then I bought all kinds of model kits and gundam body frames to make my own MP G1 TF cast, because TT was releasing one per year and was clearly never going to make anything but Prime, Megs, and Seekers. Then MP-10 changed the scale and MP-12 hit, and the 3P scene exploded to make everything under the sun. So I stopped that, tons of parts still here.
And now I'm going to have a dump truck load of spare MLs. On one hand, I assume that just means my tastes are relatively aligned with what's in demand, but it's equal parts cool and frustrating. The only thing I've had any success with was my Mega-bloks Joes, only because Mattel/Mega will never get a license for Joe... unless Hasbro buys Mattel. Now that I've said it, it's practically guaranteed.