Currencies creators sell the no arbitrage moment

The intrinsic value of the currency is nearly zero.  Under no arbitrage moments, there will be no observable gain or loss by holding the currency. Users may hold it for personal gains or losses, or loan it out to others who have possibilities of gains. But holding the currency itself is not interest bearing.

What fouls the system is the belief  among some economists that currencies bankers should impose an arbitrage moment for the economy to access.  But that is impossible to hold and the economy will always cancel that moment. In government controlled fiat systems, the arbitrage moment can be held for at most one generation, only because government tax agents are armed and dangerous.  But history shows that government  fiat systems always fail after one generation, any fiat system must eventually return to the no arbitrage moment.

So member banks win or lose based only on their business expertise.  But included in their business expertise is knowledge of how screwed up government fiat systems work, common knowledge. They know the history of regime change in the USA system, and it happens on 40 year intervals.  No problem, include that in the business expertise and everything still works, for the member banks.  People outside the system may be hurt, so the member banks can make money by helping these people hedge against the upcoming regime change.