Half the Bitcoin wealthys stash could be worth far more, later, if they would just pump half of their stash (i.e. some healthy percentage) into the Bitcoin infrastructure now. Mind you, since they hold the Bitcoin wealth, they would be investing in their own holdings.
This makes no sense whatsoever. What exactly do you suggest they do? Sell their bitcoins? That will collapse the value and achieve precious little otherwise. Spend their bitcoin on bitcoin sites? Great, but its no different than selling them and buying the stuff with dollars.
What bitcoin needs is more new users who buy bitcoins to conduct trade. That is a real influx of capital, its not the same as existing bitcoin holders spending their coins. The latter is if anything, more likely to produce an exodus of capital if the bitcoin merchant cash out (since they buy their good and services with dollars most likely).
Current bitcoin users buying, selling or hoarding coins is not what will advance (or destroy) bitcoin. Reaching a bigger public is what will make or break bitcoins.