In the first place, and on this very point, nearly all these brilliant performers were young men—in their thirties and forties—whose direct financial experience was limited to the all but continuous bull market of 1948–1968. Secondly, they often acted as if the definition of a “sound investment” was a stock that was likely to have a good rise in the market in the next few months. This led to large commitments in newer ventures at prices completely disproportionate to their assets or recorded earnings. They could be “justified” only by a combination of naïve hope in the future accomplishments of these enterprises with an apparent shrewdness in exploiting the speculative enthusiasms of the uninformed and greedy public.
――The Intelligent Investor, Chapter 9