The avoidamce of WWIII.
The breakup of the EU, and the upcoming elections in Hermany and France where the LePen fascists could come to power, supported by Putin, could spell terrible things to come to Europe. Putin would be delighted by a broken up Europe. Back to the 1800s of Russian superpower status in Europe.
We could definitely go down a path, which we will live to see, unfortunately.
This is serious stuff, and Americans should be getting some education, historical amd otherwise, before some start saluting these dangerous situations developing.
A WWIII will be an apocalypse. Both world wars started in Europe. And Churchill, De Gaul and their successors knew this was the only way to avoid a third.