By default, humans are a kludgy bundle of impulses. But we have the ability to reflect upon our decision making, and the implications thereof, and derive better overall policies. You might want to become a more robust, coherent agent – in particular if you're operating in an unfamiliar domain, where common wisdom can't guide you.
My definition was the first, which is "instrumental rationality = acting so you winyour values". So, wouldn't it say that following your gut was instrumentally rational? At least, if it's a great idea in expectation given what you knew - I wouldn't say lottery winners were instrumentally rational.