technically he said people buy stocks because they think stocks will increase in value. it is an useless/obvious observation but different from what you stated.

like cuban i do wonder why individuals think they can beat the market. well connected and well capitalized groups have access to far more information than is publicly available. with the rise of hft and the like not only are you under attack by players who understand the fundamentals better but also by people who can game the exchange platforms themselves.