My friend was excitedly telling me earlier that he found a DeFi pool with an APY, or annual percentage yield, of nearly 50%. However, within two weeks, the yield plummeted to a single-digit percentage. I was deeply impressed by his confused expression. It's not his fault; many high yields are like castles on the beach—tides, or market sentiment and incentive policies, can change suddenly, and they disappear just like that. Until I carefully studied the...