I believe that the losses you take with such fraud will be way below the inflation tax and the interest payment to the govt-financial complex.
What makes you say that?
There are various studies about consumer interest payments coming from various angles. The thing is that virtually all money comes from debt on which interest is due. Even if you yourself are not indebted, you still need to pay interest which is hidden in the price of products, services and taxes.
There was a study for my home town (Munich/Germany) about that. With a fairly typical life style you need to own about EUR 2 Million to break even - taking a profit from the debt system. Everyone else is a net interest payer.
I don't think I understand the system fully though. Could you clearly explain, what happens if Alice buys 1 BTC of Bob, but in the sending of the fiat down the chain, one node is dishonest and doesn't forward the fiat, but pockets it instead, what effect does that have on the chain, and who loses money and how is dishonest behaviour punished?
The transaction will not proceed and will time out if he tries to keep his ledger in sync with his friends but does not stick to the protocol.
If he chooses to stick with the protocol, but simply does not update his ledger, then your ledger will not agree with his. The next time the nodes try to reconcile, a QDialog will pop up, telling you that something is wrong. Your friend will find from his TX log that his ledger is correct and yours is wrong.
As you see, you can't cheat that way without getting caught red handed either immediately or shortly thereafter
As said, ZR is relying on Bitcoin to prevent the seller from cheating: A 2/3 multisig. First the seller must place the Coins out if his reach, then payment is made, then the seller releases the coins from escrow.
Its similar to the torn bank note. The escrow is necessary because there is a possible attack vector if its only 2/2: You can initiate a buy on the entire order book and then simply walk away. Doing so must be costly.