Stablecoins are supposed to be stable, and not rise or fall. There is no expectation of profit for a stablecoin like USDC. And USDC doesn't pay interest. People use it for stability and for payments.
Coinbase, who co-founded USDC, absolutely pays interest on USDC: https://www.coinbase.com/usdc
(they call it rewards instead of interest in an attempt to avoid regulation, but it is functionally the same thing)