A coin always has a downside. On average, any bank can give much greater guarantees with little interest. In general, crypto projects offering high interest rates put your money at great risk. This should always be considered.
And how many banks did not fulfill the obligation to their depositors? A lot, and a lot of examples, so I do not consider banks a reliable system.
The deposits in banks are partly insured. The works of banks are controlled by state authorities. The rights of investors in banks are much more protected then in cryptocurrency projects. But profit in banks is very small.