I don’t know why everyone here is talking about dollars, while there is zero dollars involved all the time. The author did not put in any dollars, but his ETH, which he has plenty, since he created the Ethereum thingy. That may be a large part of the answer why no one “exploited” that hole: most people would have to put real dollars in, expose themselves to all kinds of crypto gymnastics, and end up with ETH, which may or may not be convertible to real dollars where they live. And, yes, they would also have the always pleasant exposure to tax authority now (which may or may not be solvable, depending on the place of Earth one happens to live at).