Because when shit burns you can scoop up the pieces for a discount, everytime we have had massive wars, economic crises, etc its the rich who make out like bandits and centralize power even more. When you have as much excess as they have they can burn a bit of it so things go on sale, if the us dollar loses half its value they are still billionaires and can buy up a lot more assets all the while the poor have become even worse off with no ability to get any assets.