and roll over the rest of Europe without American support in a matter of months...

I think you are quite mistaken. Europe can mobilise a far larger force, and the weapons already on site will do the job. Not that it matters, because Russia would not attack Europe openly anyway, because it wouldn't just be Europe in the fray. Europe still has actual allies.

Europe can't compete with American businesses due to the vast difference in work ethic and productivity.

Again, I think you are looking at it historically. I have worked closely with Americans. Long hours don't mean productive hours.