On Kongregate, 2.1% of users buy virtual goods. Of these, about 4% (the whales) have spent over $500 and bring in about half of Kongregate's revenue. Top spenders often spend $50K-$80K.
Emily's premise is this: that people who spend lots of money on games (whales) are people who healthily enjoy the games as hobbyists.
Her most interesting points, in my opinion are as follows:
We think whales are bad (but shouldn't) because they spend their money on virtual goods: "Spending $5-$10k on specialized PC Gaming rigs that improve your skills and enhance your competitiveness is not really that different from spending money for in-game items that do the same. But I bet you all find it a lot easier to contemplate."
We think whales are bad (but shouldn't) because we don't think games are a legitimate hobby: "The bias against games is so insidious that even within the industry we’ve internalized it enough that we question someone with means spending tens of thousands of $s on a game, especially when you combine it with the low value we place on mobile and PC games and especially virtual goods. And so people jump to explanations like “mental illness” or “evil games manipulating players” when the real explanation is that they are rational, wealthy people who are dedicated fans investing in a particular game."
I personally don't agree with her though. We would have no problem with a person spending $10K on software. The issue isn't virtual vs. physical goods. The issue comes down to if games are a legitimate, healthy hobby or not. I would argue that they are not, at least for most of those who are whales. I don't have time to flesh this argument out tonight though.