"The wall works"
Short-term maybe.
The Berlin wall didn't work.
The Israeli wall isn't working.
Closing the gates on your castle of wealth and consumption and trying to barricade out the huddled masses will lead to revolution, war, or collapse of civilisation, in the long run.
You have to find a solution that works for everybody, including those not in your country.
What if you built a wall and everyone ELSE enforced it? No oil in, no manufactured goods out?