From the linked WSJ article [1]:
"The Bwin data also offer a peek at the economics of the casino industry that only insiders normally glimpse. Among the findings is an extreme reliance on revenue from a small number of gamblers.
Of the 4,222 casino customers, just 2.8%—or 119 big losers—provided half of the casino's take, and 10.7% provided 80% of the take.
Such revenue concentration long has been quietly acknowledged in the casino industry, but the Bwin information may be the first to show it with hard public data."
Compare that to the f2p industry. From Re/Code in February [2]:
"In a mobile monetization report released today, app testing firm Swrve found that in January, half of free-to-play games’ in-app purchases came from 0.15 percent of players. "
"Some game companies talk openly about the fact that they have whales, but others shy away from discussing them publicly. It costs money to develop and keep a game running, just like those fancy decorations and free drinks at a casino; whales, like gambling addicts, subsidize fun for everyone else."
[1] http://online.wsj.com/news/articles/SB1000142405270230462610...
[2] http://recode.net/2014/02/26/a-long-tail-of-whales-half-of-m...