My guess is that those who level the accusation are aware that they themselves are envy-driven individuals and assume that this is a common feature of our fallen human nature. And who's to say they are wrong? Certainly it's not difficult to think of lots of supporting evidence regarding the roots of our motivations. Personally I honestly can't figure out if my envy of their 'success' lies at that the heart of my fairly obvious animus against the kind of bankers who precipitated the latest crisis in our markets.
But even if it is pure envy on my part, and that of all the protesters, I also can't see how this makes any difference regarding what is happening. If envy is a reasonable motive for trying to out-do your fellow man in the marketplace, and as far as I can tell the world of Capital thrives on that notion, why would it somehow undercut people's protests against other people having cornered far too many of the world's resources just because they are envious of them? I suppose the argument then would be for 'good envy' - the type that drives you to work hard and succeed in the marketplace - as opposed to 'bad envy' - the type that leads you to stick a metaphorical bomb under said marketplace. But the problem is that if the marketplace is seen to have failed the vast majority of those in it - and we seem to be looking at a storyline with this worrying ending tacked onto it - then it doesn't seem to matter which species of envy is operational.