How are DeFi yields so high?

Could you elaborate on why decentralized finance (DeFi) yields tend to be so high? I've noticed that compared to traditional financial institutions, DeFi platforms often offer significantly higher returns on investments. Is this due to the innovative nature of DeFi protocols, the lack of intermediaries, or perhaps the higher risk associated with these investments? I'm curious to understand the underlying factors that drive these high yields and whether they're sustainable in the long run.