Based on the current circulation of USDC at 60 billion USD, in the ideal scenario, holding all government bonds:
In one year, you can earn 600 * 0.04 = 2.4 billion USD in profit. If you were the owner, would you sell Circle (the issuer of USDC) for 5 billion USD?
Ripple once offered 4 to 5 billion USD in an attempt to acquire Circle, but was rejected.
https://chainalert.me/view/headline/c6c594
The formula is principal multiplied by the government bond yield:
USDC issuance data:
https://chainalert.me/data/stable
Government bond yield data:
https://chainalert.me/data/us10yrbond