Idiots, all.
If the USA never happened, Its safe to say that Europe would be one large NAZI state. That 'free healthcare for all' would involve camping trips and showers.
Actually, without the US, there is a decent chance that Germany would have won WWI, there might be a large, German Empire, Austro-Hungarian Empire, and Ottoman Empire. If Germany had won WWI, it would still have been a monarchy, so Hitler would not have been elected, unless something else encouraged Wilheim II to abdicate the throne.
However, if we were still part of Britain, they would have still had our manpower, though considerably less without the Louisiana purchase and subsequent spread westward, and we would have joined WWI quite a bit earlier, as Canada did, so maybe the war would have been over faster as well. That is what makes What-If history so interesting, if you change one little bit of history, it has an effect on everything that follows.