But Taleb's point is that (non-insiders) cannot accurately predict regarding individual securities (hence derivatives), but can identify over-/under-priced OTM options — and that, trading these systematically, one can suffer many repeated "small" losses that become outweighed by the Big One that eventually (yet unpredictably) hits, thus generating overall positive expected value. But, as I further understand Taleb, most people don't have the huge capital that enables such a strategy, and that doctors, lawyers, dentists, etc., are better off making money by plying their professional services and perhaps investing in index funds and the like.