Dynamic Anchor Earn Rate

Banks do make such high profits, giving only 0.25~4% back to depositors . As DEFI replace banks system, the APY is fully giving back, I think there must be a way to be sustainable other than changing what makes Anchor so special and different from other curve lending platforms.
Could the deposited UST which is not used by the borrower be used for extra safe investment/farming?
What about dynamically limiting the Earn deposit amount ? based on a sustainable lend/borrow ratio, where the ANC coin could play a role. I am no expert.