At the right price people will buy anything.
An FX-83xx is a decently capable CPU in 2016. It's a poor choice of starting from scratch but is capable of playing most games smoothly. Its biggest drawbacks are not its gaming performance in most AAA games, but rather that due to its low single-threaded performance there are a small but significant number of games it will perform poorly in, that it's on a dead-end socket with no future upgrade possibilities, and that it draws close to three times as much power as an equivalently performing and priced Intel chip. I'd still consider it an option if you have a compatible motherboard though, because a $120 FX CPU costs significantly less when all is said and done than an Intel chip, motherboard, RAM, and copy of Windows... unless you can get a fair bit from selling your current parts.