There's at least one thing to stop them: fundamentals and speculation. People buy back in (in part) because Bitcoin is designed to strengthen itself (not price,

There's at least one thing to stop them: fundamentals and speculation. People buy back in (in part) because Bitcoin is designed to strengthen itself (not price, I'm mainly referring to incentives to mine and to steward). (And it's not equivalent to the shitcoins that it spawned so the assumption it it's not special is invalid.) That makes Bitcoin a completely different asset to model than a fiat currency. If there's one difference, there are probably more. And there certainly are.