Yes, so "poor performance" is simply not a consequence of cocaine use. There are other numerous disadvantages to health and of course the risk of addiction for that 2% from using cocaine, primarily from the good euphoric feeling one gets from it. That's why high-functioning, high-performance and very successful people are the primary users of cocaine. They're also the the ones who can afford it. The poor folks use the "crack-cocaine" which is more dangerous and less desirable, highly addictive, but cheaper version.