So, whether a blockchain is used or not, there's no way to know that I'll get what I paid for or an empty text file.
So the blockchain serves no purpose in this instance.
Asking people to send you money, and them trusting you'll send them the exploit is exactly the same and no blockchain is needed (except maybe the bitcoin one, since of course you don't want to use paypal)
So the blockchain serves no purpose in this instance.
Asking people to send you money, and them trusting you'll send them the exploit is exactly the same and no blockchain is needed (except maybe the bitcoin one, since of course you don't want to use paypal)