“Violent crime in the UK is FAR lower than in the US. For example, last year NYC had 352 homicides. London, with the same population, had 118.”
You missed the point. They immigrants are driving up the crime rate. That’s why they want to stop the open borders.
Furthermore, supporting millions of immigrants is extremely costly.
When you measure their GDP in terms of dollars, it went down (temporarily), but in the pound life will go on as usual. Again I believe that things will go back to normal in a few months to a year. That will give impetus to other countries to exit.