Banks run on interests and for that reason their are also after the charges the get from the customers and even though their have a stable coins, their interest generation and operations that generate the interest their could pay to customer holding those banks stable coins can't be compared to that of an exchange.
Take for example, how many Banks can generate the daily trading and staking and other Centralized exchange like binance volumes and cap.
Yea you are right, but it can simply be that people are tired and sick of banks BS. Banks can be inconsistent and people don’t find their services attractive. Looking at the long term challenges that can come from bank is enough to for exchanges.