A question: Why don't flash loans require collateral?
Flash loans let users borrow and repay funds within the same transaction, without collateral.
The borrowed funds and fees must be returned to the liquidity pool before the transaction ends; otherwise, the entire transaction is reverted, as if it had never happened.
To use flash loans, you need to write your own contract or use specialized tools. Be especially wary of software claiming to make flash-loan arbitrage easy.
The lending protocol Aave, associated with $AAVE , supports flash loans.