Why is a single entity needed to back a currency. Isn't bitcoin just crowd-funded vs. the the US is the dollar's vc backer? For it to truly crash, everyone who

Why is a single entity needed to back a currency. Isn't bitcoin just crowd-funded vs. the the US is the dollar's vc backer? For it to truly crash, everyone who uses it for different reasons would have to decide it is worth less. Bitcoin is a protocol for money. Protocols, once they have acceptance have a pretty great shelf life. See http, tcp/ip. So long as they get the job done, there's a disincentive to replace them once established.