If you're talking about knowing the direction of prices, which is what everyone really cares about, then both laymen and Wall Street start out on almost equally

If you're talking about knowing the direction of prices, which is what everyone really cares about, then both laymen and Wall Street start out on almost equally bad footing - they can each have only small predictive edge at best at best in a highly probabilistic game. So a smart and disciplined investor can do as well as or better than wall street mostly by avoiding dumb mistakes.