It's bound to happen with old GameBoy cartridges, but it seemed to happen to a decent number of Pokemon Red and Blue cartridges. Did you ever own a copy of either game and had a cartridge that would lose saves on a regular basis, leaving the game mostly unplayable? It happened to me once, and it was a little annoying to say the least.
No, this never happened to me personally. But it did happen to a few friends around the time we all got nostalgia for the games after hearing some creepypasta about the older versions. Of course, under this context they were creeped out; but the games were thankfully just corrupted from misuse or something akin to that by previous owners.
It happened to me with my Pokemon Emerald! I was gutted. I'd play, get far, and then the save file would be lost.
It happens most often to the pirated games, since they don't include the necessary hardware to properly function. Another possibility is that the cartridge's battery has run dry and a replacement is needed.
