Nothing fell apart, its all part of the process, just like the dot com bubble and bust, crypto/decentralisation is not going away. Economics always wins. Someone will make a better, regulated version, that works.
“No demand”. Isn’t Bitcoin still trading for several thousand dollars? Maybe you, and maybe most people, don’t have any want for cryptocurrency, but don’t let that make you think that nobody has demand for it.
Most of the increase in transactions you see now are from HFTs speculating, who generate demand on any high-risk instruments if they think it has a return somewhere. Demand for Bitcoin as an asset isn't that different from any other commodity, but demand for Bitcoin as a currency is not there as many competitive substitutes exist.
And that's when the transactions are even real. There's significant evidence that >80% of volume is wash trades used to drive traffic to fraudulent exchanges.