GBTC market cap is $37bn. USDC has a market cap of $7bn+. CME future contracts are also in the billions. No one knows for sure how many bitcoins are changing ha

GBTC market cap is $37bn. USDC has a market cap of $7bn+. CME future contracts are also in the billions. No one knows for sure how many bitcoins are changing hands privately (offline liquidity). Tether is just one of the venues of trading with bitcoin.