People are still using "De-Fi" on ETH because of the hype. After all, they're only into it to make a lot of money in the least time possible. Fees will only get higher as more people join the crypto/Blockchain craze. Other blockchains like Solana and Binance Chain have cheaper fees and faster transaction speeds, but they have a small library of dApps. Ethereum has the biggest ecosystem of dApps and services around it, so it's unlikely another contender will be able to take its place in the future.

One thing for sure is that "De-Fi" is not constrained to a single blockchain network. This gives people true financial freedom. If fees are high on Ethereum, there's always a "Plan B". Only time will tell us whenever "De-Fi" will become a success or a failed experiment altogether. Just my thoughts