I first learned at a young age of the efficient market hypothesis from Malkiel's Random Walk Down Wall Street. Rather than dissuading me from investing, it gave me confidence that if the theory's right then my choices should perform about average anyway. And if it's wrong, then I would have a chance to do well if I did my homework. I've done alright, but realized pretty quickly that it's much easier, more predictable, and less stressful to invest in my education and job skills. Investing in these can easily gain you seven figures additional cumulative income over your lifetime, something quite difficult to achieve in investing without either large starting capital or a very large edge.