Classic case of Texas Sharp-shooting, painting bullseyes around the bullets.

"A sufficiently smart person will always find a way to overfit any model to get to result they want".

Or "If you torture the data long enough, it will confess"

But this case looks like an outright fraud. The paper doesn't even show the strategy that led to very high returns. It just shows the results. And this was a peer reviewed paper in the top-4 marketing journals.