Last time I loaned btc was for margin trading at Poloniex. Was very profitable as this was running up to the 2017 boom, but I was lucky. They had a huge liquidation event on some defaulting bug several months back didn't they? And they "socialised" losses so guaranteed income from lending does not exist. Even if funds were somehow non-custodial (escrowed or timelocked maybe by smart contract), any decision to socialise losses from bugs would lose you money.

People are saying the industry is showing signs of heating up impending collapse. I'd consider something else. Too high risk for too little gain.