Thank you for the compliment, but it's a simple answer, the borrowers are paying the high APY, or I should call traders
you can go to aave.com and see the rates, that's the biggest smart contract lending/borrowing platform
You think 40% APY is high, and the borrower is probably paying over 50%, but it's not a big deal when you're only borrowing for a couple of weeks
There's very little risk as these loans are over-collateralized, meaning in order to be able to borrow $10,000, you needed to provide over $10,000 worth of cryptos (btc, eth, etc)
When we had the crash in May/June, the cryptos ecosystem lost over $1T of value, what happened to all these loans? Some traders got rekt, got liquidated, lost their collateral, which could be Eth, btc, etc
None of the CeFi platforms (Coinbase, Binance, Kraken, Kucoin, etc) shutdown, did they?
Did you hear of problems with DeFi AAVE platform shutdown?
Over $1 Trillion worth of value and nothing happened to the cryptos universe

Market cap is all time high on cryptos again
So maybe, it is not as risky as you think it is...
Rates are high because there are a lot of degen traders who want to take advantage of the bull market fomo and don't want to sell their cryptos so they borrow against it to trade, and get rekt...
What do you think would happen if the same thing happened in Wall Street and they lost about 50% of value in a few weeks time?