I'm sure that extraordinary expertise at economics would enable people with the right mindset to make large amounts of money, but the obvious avenues (e.g. spending all day trading stocks) would not interest me, and I'd be unlikely to value the money enough to put up with them in the quantity necessary to become massively rich. If I magically acquired extraordinary expertise at economics, I'd probably mess around with it until I had enough money to hand the reins to a less-skilled accountant to handle and invest for me and keep me in housing and groceries for the rest of my life. I'd be more comfortably upper-middle-class than rich. It's possible that my extraordinary expertise at economics would also inform me of fun ways to make money with it, but none spring immediately to my unskilled-at-economics mind.