So we lose thousands of soldiers, just because some people were idiotic enough to go to Europe in the middle of a war.
Russia lost the worst - they surrendered to the losers and ended up with communism. Austria Hungary lost second worst - they lost about 3/4ths of their country and were stuck with reparations that crippled their economy until 1939. Germany came third worst - they lost their overseas colonies and wound up with the Polish corridor running through their country. Reparations and political upheaval collapsed the economy and ultimately lead to the Nazis.
The US didn't come off that bad by comparison - all we lost was a lot of good men and a measure of our freedom due to the expansion of the power of the central government, something that happens every time we go to war.