That crypto currency can be more secure than money in the bank.
So some people will be charged with negative interest rates. The cost of having money in the bank therefore is going to be significant.
In addition there is risk of having money in the bank (bank could go broke etc).
Now think about these folks could simply convert their fiat into a stable coin, use a defi platform and earn interest.
The thing is, a stablecoin like DAI has none of the problem money in the bank has.
Just imagine what this could do. I cannot wait for people and companies to realize this.
No-one seems to get this, otherwise the interest rates would not be this outrageous. But I am sure this is simply a matter of time to propagate.