This is a new spin on an old phenomenon. For banner advertising, a tiny percentage of the population (< 10%) contributes a massive percentage of all display ad clicks (> 80%). She's disproportionately a lower-middle to lower-income older American female in the Midwest who plays the lottery and subscribes to Reader's Digest. Totally not joking. A word often used to describe this segment is "compulsive clicker."

Online publishers are well aware of this and, well, do not go out of their way to highlight this fact on their rate cards. Instead they'll provide their audience information and often do not mention that they know their typical click is not representative of their audience. Given that they're the "whales" of the CPC business model, they're frequently not quality-priced down to zero, unless they so dominate an advertiser's campaign that the advertiser complains.

There are related issues with almost all online advertising. One should be very attentive to the default settings at one's major advertising network of choice, because the default settings almost always group the prime rib cut of the attention market with the pink slime and sell it at prime rib prices. (Examples: there are strong differences in pricing with regards to user location. Many advertising platforms, ahem, make it very straightforward for American advertisers to advertise their wares to users in developing markets. All you have to do is not opt out.)