They buy btc to back up their currency USDT so that's what the money should be backed by btc. The digital gold.
Think about the fiat currencies every dollar bill in your pocket are debt the USDT seems much more reliable then fiat, USDT can and it should decouple of dollar If the dollar value don't go up.
Me and many others like to see one day USDT paper currency also. I rather hold new dollar (USDT) Then just the current dollar wich is debt structured.
The path to financial freedom comes first we need to get rid of the debt based economy so the real way Will be USDT backed by digital gold the btc and other digital currencies.
Goverments also can function better If they buy btc and whatever budget they need , for example to fix health care or to build up something then they might sell some part of their btc to get USDT instead of using debt and making inflation high they can use sound financial system.
So instead of taking the loan goverment can buy dca way BTC with tax payers money and If btc price goes up they can sell and with that funds they can a lot good things in society.
I don't know about USDC but USDT financial structure looking more solid.