[The Congress shall have Power . . . ] To coin Money, regulate the Value thereof, and of foreign Coin, and fix the Standard of Weights and Measures; . . .
Because Article I, Section 10, Clause 1 of the Constitution prohibits the states from coining money,
1 the Supreme Court has recognized Congress’s coinage power to be exclusive.
2 The Supreme Court has also construed Congress’s power to coin money and regulate the value thereof to authorize Congress to regulate every phase of currency.
? Not how I understand it. I can start a currency, the trick is getting someone to accept it
https://constitution.congress.gov/browse/essay/artI-S8-C5-1/ALDE_00001066/
Feds won't easily give that up to a state run bitcoin/trash-token.