People often repeat this (also in different contexts, e.g. driving skills) as a "proof" that most people don't know math. In fact, it's the other way around -

People often repeat this (also in different contexts, e.g. driving skills) as a "proof" that most people don't know math. In fact, it's the other way around - a proof that the person suggesting this doesn't know math. If 80% are skilled at 1 and 20% are skilled at -100, then most are better than average. Or: Imagine a room of people. Bill Gates walks into that room. Most people are now below-average wealthy.