Remember when the buttons test was circulating a few months ago? Where if you press the red button, you survive, but if you press the blue button, unless more than 50% of people chose the blue button you die? That was a case very similar to this. It is locally optimal for everyone to choose red; your own outcome is always better or equal to what it would have been if you chose blue, however everyone independently making this optimal choice is catastrophic on a global scale. Thats why its "rational".