DOUBLE SPEND ATTEMPT #3: (succeeds once and a while)
3-A. Back at the lair, you realize that your quest for free coffee is more difficult than you actually thought. You call up some nefarious miner that controls 30% of the global hash power. You tell him that when you give him the signal, he should add your fraudulent transaction to his memory pool of unconfirmed transactions. You pay your iPhone hacker to modify your app to send the evil miner a special signal when you buy your coffee.
3-B. You go to the coffee shop and buy your coffee. Your new app sends the signal to the evil miner that you're in cahoots with. The miner adds your fraudulent transaction, while the real transaction propagates across the network.
3-C. Since the evil miner controls 30% of the global hash power, your coffee is free 30% of the time.
3-D. Finally, you succeed! You also decide it is a lot less work to just pay for your coffee normally...
Again great argument, you will only succeed at scamming 30% of the time lmao, what a joke this place is.
Yes, you will succeed at scamming 30% of the time for zero-confirm transactions
if you are in cahoots with a nefarious bitcoin miner who controls 30% of the global hashing power and if he is willing to risk his reputation and waste his time (and multi-millions of dollars of equipment) helping you steal coffee.
Perhaps you didn't see the hyperbole in my post: the point was to illustrate the worrying about something like this actually happening is stupid for anything but very high-value transactions.
