Whilst the USA and Russia were making money and friends with Hitler, the Commonwealth countries fought alone in North Africa, the Middle East, Abyssinia, Scandinavia, and across the oceans of the world. Between 1939 and 1941 the UK, with the full effort, support and sacrifice of the Commonwealth, fought alone against Hitler and Mussolini, bribed Franco to stay out of the war, and died for liberty.
The USA took money from both sides, enjoyed the profits of slave labour and stolen companies in Germany and helped arm Japan. If Japan hadn't bombed Pearl Harbour, and Hitler hadn't declared war on the USA, they would still be counting their ill gotten gains. In terms of goods and materiel, the USA gave nothing. It was all bought and paid for, the debt was only paid off a few years ago. In terms of sacrifice, nobody can take away the heroism of US troops. However the role of the USA is a murky one which few choose to delve into, for fear of what they might find.