Funds move between users inside the smart contract, which is orchestrated by validators and guardians. When a contract is open, validators package transactions into blocks. Elected by guardians, validators have a near-perfect probabilistic guarantee of participating honestly with safety features such as built-in collateral (to disincentivize cheating). Users also decide when a contract closes, sending funds back to the main ethereum chain. In other words, the funds are always #safu.