In this specific case, they are exposing themselves to risk from the time value of money, the capital price of the bond. If rates rose 0.5%, they lose 3% on a 7 year bond.
Edit: Ok I admit defeat here. I don't think the costs are anywhere near interesting from a where-does-my-tax-money-go perspective, but I concede that the Mint must spend some amount of money on it. I won't delete the comment for historical purposes but consider it retracted!
The mint was eating the entire credit card transaction cost, so that $300 came from the mint, and probably more as well. Not to mention the shipping charges, and the cost to re-process all of those coins when they came right back to the mint. The line item profit to the mint is still positive since it cost way less than $15,000 to make those coins and they can re-sell them. But in reality, it just means that either the mint prints more dollars to make up for the loss (taxpayer loses in inflation) or more taxes are raised to pay for the loss (taxpayer loses more directly).
The bank where he deposited the coins also was forced to eat processing cost and shipping charges to return the coins to the mint. If lots of people started doing this, the bank would end up having to raise rates, charge for the service, or put significant limitations that would hurt legitimate usages (ex: laundromats).
All in all, this is a naughty hack. The hacker came out ahead, the credit card company came out ahead. The bank lost a little, the US government and taxpayer lost big. The economy as a whole loses as well - a lot of busywork was created, but no net value.
Oh and there's shipping. 300LBs anywhere isn't going to be cheap.
Why won't depositing these coins into the bank get them into circulation? It has to be either because the bank won't hand them out unless you specifically ask for them or because people don't want them. That's a sure sign that a coin is DOA.
I find it in my best interest to make it as easy as possible for clients to pay me. If I have to pay a percentage point to make it easy for a client to hand me money, I'll gladly take that as a cost of doing business.
Iraq|Healthcare|Welfare|NEA|USPS
Better a taxpayer get back some stolen funds from the government than have it thrown away in another country, or on bloated pork.
The people he's getting his money from is his bank/credit card company. If you want to say "screw you" say it not as a tax payer, but as a consumer of credit cards, who will eventually have to deal with higher rates/restrictions/limitations on rewards.
He gained about $200 worth of airline points, and taxpayers are out about $1000. Sounds like a good deal to me. Or not.
Second, if he only got $200 out of the deal, his fault. I personally make $20 per $1000 in cashback.
Could they in theory issue a 100% cash back card that the merchant gets charged 100% on? How is the merchant supposed to know what they are getting charged when the swipe a given piece of plastic?
http://www.braintreepaymentsolutions.com/blog/Costco-your-ma...
I have no idea if what you proposed is possible, but my guess is that no one would accept that card :) I don't accept amex because I think it represents a fraction of actual users, and those users have other cards because they are used to getting told "nope, sorry don't accept amex".