For me it lasted longer than I thought it would be. DEFI according to my idea are highly efficient way of doing doing P2P exchanges, P2P loans and other financial activities that would not involve a middleme. When there's no middlemen, the users would be the one that's rewarded most. The platform too makes a profit but the profit made by the platform is a small fraction, which itself can be high if they can move large volume of coins. i.e. for a Defi to sustain, they should have lowest fees and large volume. For that to be true, there would be just a small number of successful Defi and in no way would it be money generating machine for investors.