DeFi protocols' revenues

The still relatively young DeFi sector is certainly attractive to investors because it can generate revenue in a permissionless way while keeping the operating costs very low. 

The vast majority of revenue is still distributed to the supply-side, like lenders or liquidity providers. In the same vein, centralized exchanges incentivize market makers with reduced fees or rebates. Without economic advantages, liquidity on exchanges and protocols would be severely limited due to the more significant risks.