Very true. During WW2, Russia lost 14% of its population. 24,000,000 casualties.
First of all that statistic is questionable, but let's agree that the figure was enormous. As I have asserted above large numbers of Soviet casualties were brought about by their own attitude to their troops. In addition it is certain that millions of civilians died of starvation. Leaving aside those who died in the siege of Leningrad, the disastrous agricultural policies of the 1930's left the country ill-prepared for war, and unable to feed its people.
Russia certainly fought bravely and ferociously, but its casualty list is an unreliable indicator of its overall contribution to victory, which in a global sense was certainly less than that of the USA. The USSR, for example, did not declare war on Japan until August 9th, 1945, three days after the Hiroshima bomb, when its troops entered Japanese occupied Manchuria. Their contribution to the war in the Far East, therefore, was virtually nil.