I think experience from long term investing teaches you humility. No matter how smart or confident you are the market will teach you humility. Once you become humble then the market will deliver you returns. In alot of areas of life wrong ideas or opinions are never challenged or corrected but the market will always correct wrong ideas or opinions. Then even if or when you achieve success it will not go to your head because it was the market that brought you the success. Therefore i think stock market investing is good for your general thinking. In the irish political system wrong headed thinking has never been challenged or corrected, the system that propagated the celtic tiger is still in place.