Because they go bad a lot these days so to a cps1 collector with his head screwed on straight they are more valuable to hold onto to fix a future problem than to sell for the current going rate. And yeah they aren't worth paying to have fixed unless you are just extremely into hardware preservation. It will probably cost you more to ship it back and forth than the board is worth even before a repair cost. You could pick another game you are interested in that uses it and buy that as a complete boardset then switch between games by swapping the motherboard. Or wait for one to pop up on ebay. It does happen from time to time.