Without America the world would be a horrible place. People forget that the stock market crash in 1929 almost sank all boats as far as world powers go. The 1920s weren’t just roaring in the US. Germany was too. The only major countries that came through the crash unscathed were Japan and Italy, who incidentally were our allies in WW1.
A mangled America now would also sink several boats and have us isolationist out of necessity. Our military would be mostly occupied going after terrorists and massive cartel gangs here. Our global reach would be seriously curtailed. It’s what the left wants.