Parallel economies are banned. Try making a new currency in the US.
https://www.armstrongeconomics.com/history/europes-economic-...
https://collectingpapermoney.spmc.org/wiki/Scrip_Issued_duri...
Governments love crypto because it lets you seize lots of money from criminals across borders. And it is legal gambling where you can tax the winnings without reimbursing the losers (unless they can offset it but most probably can not)