"Consider the Ether.fi liquid ETH vault, the second-largest borrower on Aave, with roughly $1.5 billion in outstanding loans. The strategy is straightforward: supply weETH (≈ +2.9%) and borrow wETH (≈ –2%). The vault charges a 0.5% platform fee on TVL.
Of Ether.fi’s total TVL, approximately $215 million represents net liquidity deployed on Aave. This generates about $1.07 million per year in platform fees for the vault. The strategy pays roughly $4.5 million in interest fees to Aave, (calculated as $1.5B in borrowings × 2% borrow APY × 15% reserve factor).
Even in one of the largest and most successful looping strategies in DeFi, the lending protocol earns several times more than the vault operating on top of it"