Europe's (and our coming) Tragedy of the Commons
The gist of the tragedy is that commonly held (important) resources will be depleted and will not be replenished. And this doesn't apply only to how the wilds are being ruined by being held in common but also to national treasuries which everyone in a country believes is there for him or her to dip into indiscriminately. And then, with international communities, the tragedy isn't contained by national borders.