It’s not my thought, but as Peter Bernstein pointed out in Against The Gods, it took three years for Black & Scholes to figure out that Risk was the downside view of Volatility– and they were smart enough to win the Nobel Prize in Economics!

The probability that the price of AT&T stock might go up–or down–is irrelevant. The only thing that matters is how far the stock price might move, not the direction in which it moves. The notion that the direction of price change is irrelevant to the valuation of an option is so counterintuitive that it explains in part why Black and Scholes took so long to come up with the answer they were seeking–even when it was right in front of them.

–Bernstein, pp. 312-313, emphasis and any transcription errors mine.