Because when the super-wealthy collaborate, it's usually on stuff that benefits them, to the expense of everyone else, e.g. software patents, copyright extensions, and trade agreements with all sorts of fun stuff hidden inside: https://en.wikipedia.org/wiki/Trans-Pacific_Partnership_inte...

When money is equivalent to speech, it's very easy to shout people down.

"People of the same trade seldom meet together, even for merriment and diversion, but the conversation ends in a conspiracy against the public, or in some contrivance to raise prices."

-Adam Smith

Well, considering the wealth and power concentrated in those rooms during the meeting, these people would have a good shot at foisting whatever system they want over the world. I'm not arguing it should be disallowed, but it is disconcerting when every billionaire in the world might agree on the same set of policies.

Not endorsing the guy in this video and don't know much about him personally. With that disclaimer, if you watch this video his lampooning of these meetings as an insider is quite hilarious. https://www.youtube.com/watch?v=dbfBi-O8ijg#t=11m45s