It’s definitely a productive mindset to have, just look at Trump and what he achieved against all perceived limitations, but even he is a deeply limited person in many ways and deep down knows it.

Alexander the Great is probably the closest a human ever got to being limitless, he thought of himself as a god and acted accordingly, completely changing the entire known world in just a few years. If you were limitless you would be a god among men like Alexander, reshaping the entire world to your liking, charging into battle in the front row as if no human can harm you, etc.