Bremermann's limit, (or some extension of it?), says that the minimum amount of time needed for a system with average energy E to change to an orthogonal state, is inversely proportional to E (specifically, pi * h_bar, all divided by 2E ).

So, assuming that “I have the money” and “you have the money” are orthogonal (collections of) states, then there is a maximum rate at which the system can switch between those states.

You might say “well, what if we just count the number of transactions that ‘should’ have happened, instead of counting the number of actual events where the money changes hands”, but that seems to obviously not reflect actual benefit?

If me and another person turn away from you, and then turn back, and claim that we exchanged ownership of a dollar bill I’m holding 2^64 times while we were facing away from you, the obvious response would be “no, you didn’t.”.