If someone 'buys' $100 and doesn't/can't (by lack of professionalism) use it, $75 remains after 1 month, after 2 months it's worth $ 56,25 etc.
After a year the original $100 has been reduced to $4,22, without any 'service' being delivered.
In the meantime the 'EF-bank' can make a profit of x% investing the $100 elsewhere.
In our legal system we call that a 'con' scheme for which you can be prosecuted.