Zero-sum Thinking and Resultant Slowdown at the Heart of Economic Stagnation, BREXIT, and MAGA-nomics

The UK's GDP growth per person slowed dramatically from 2.5% to around 0.5% annually following Brexit—a drastic change, largely attributable to the economic effects of Britain's withdrawal from the EU and the global economy.
Just as Britons narrowly voted for Brexit, we Americans might similarly (and narrowly) vote for Trump, potentially embracing policies that involve withdrawing from the global economy through tariffs, deportations, and other isolationist measures. If so, we could experience a comparable economic slowdown, starkly contrasting with the thriving economy of recent years.
This isn’t surprising. While economies are complex and unpredictable, one certainty is that zero-sum thinking—where gains are seen only at others' expense—leads to economic decline. The mindset behind Brexit was that Europe was prospering at Britain's expense, just as Trump's supporters believe that the world is prospering at the expense of the U.S. Zero-sum thinking is not only the root of conflict but a path to scarcity. Unfortunately, it’s also at the core of both Brexit and "MAGA-nomics."