Passengers don't leave 50,000 ton ocean liners for wooden boats without motivation.

Brexit is a symptom, not the problem.

Within 24 hours of the Brexit victory its disruptive effects made many argue it was a mistake; that it would not be long before a repentant Britain was pushing its face against the cold glass doors of the Euro cafe, wistfully eyeing the delicacies now out of its foolish reach. Yet others have argued in the same breath it would be Europe with its face pressed against the glass, longing the other way round....

Douthat's observation it was a pre-existing crisis in the EU which brought about Brexit must be taken as central. Countries don't usually walk out on a good thing without a reason just as passengers don't leave 50,000 ton ocean liners for wooden boats without motivation.