I attended the July camp, and it would be reasonable to say that I was "surrounded by other ambitious, successful, practically-minded folks". Quite a few of the other attendees were entrepreneurs, though it was not targeted specifically at entrepreneurs like this one seems to be. Many others were computer programmers (like myself) and academics. The opportunity to interact with the other attendees was a valuable part of the camp.

Hang out with us! Seriously though - the minicamp in 2011 included people involved in Microsoft, Valve, Google, some hedge funds, Addepar, The High Impact Network, and a variety of entrepreneurial endeavors. At least half of the attendees were successful in academia, though I can't brag as much since I don't know anything about academia.

And that minicamp was FREE. The $3.9k pricetag this time around seems to strongly filter in people who are serious about self improvement (ambitious, practically minded) and who have access to money (successful).

Not sure what kind of evidence you're looking for here; that's just a description of our selection criteria for attendees.

I have attended the very first workshop last summer, and it was filled with very intelligent, very driven, and very passionate people. The level of sanity was much higher than anywhere else.

As another data point, I attended the May camp, and one of the most valuable things (though certainly not the ONLY valuable thing) I got from it was being around, and conversing with, all the Awesome People there, and plugging into that social network.

Because there is a pretty intensive application process (I think less than half the applicants were selected), the attendees were all People I Wish I Could've Spent More Time Talking To, and the teachers themselves were exemplars of the characteristics listed.