It doesn't guarantee it, but I've noticed even with myself (by no means "rich") that as soon as the money didn't matter (in any near-term sense), I became a better investor.
It's the same as playing no-limit poker. If I'm playing my best, I'm playing in a way that I think of the chips (money) as a tool. As soon as I start thinking about it as spendable money, I might as well get up, because I'm not going to be playing at my best.
I can readily imagine that the rich get superior returns by finding solid financial prospects that aren't accessible to Joe Main Street who can't afford to tie up $1MM for years.
What I see happening in the Florida real estate market, where PE/hedge funds are vacuuming up foreclosed properties is exactly the type of "smart money" investments differentially available to rich people. (Sure, there are REITs, which are accessible, but there someone is already fattening themselves up on part of the profits from the activity.)
So, not all of these are guaranteed high-alpha investments, but I find it hard to imagine that there aren't pockets of alpha out there that are preferentially accessible to the rich.
The article is a media play-pageviews and ad shows is the primary purpose, not winning a Pulitzer Prize...