>>The only reason flash loans even work with no collateral is because you can be sure nothing else is running on the “world computer” while your transaction run

>>The only reason flash loans even work with no collateral is because you can be sure nothing else is running on the “world computer” while your transaction runs, so you can roll it back with no risk except gas fees. The more important reason flash loans work on Ethereum is that Ethereum runs programmatic contracts that can take the output of a function call from a different contract as their input. This is something that doesn't exist outside of the world of smart/programmatic contracts. The blockchain just provides the immutable ordering of transactions and credible neutrality of access-control needed for the state of programmatic contracts to accrue value.