Most rich people aren't sitting on piles of cash; their capital is (usually) invested in a corporation which is busy turning potential into action, as you put it. I think there's an argument to be made that amassing and hoarding great wealth, particularly near the end of one's life with the intent to pass it directly onto one's heirs, is morally questionable if you believe in any kind of universalist ethic. But I think criticizing someone as uncreative simply because they're not selling off all their equity to go pursue some other venture is way off