I’m not as cynical as you are.
But, my view of WW2 has evolved to this, over the years. This would be FDR cutting a deal with Stalin:
“OK, we agree that Hitler has to be stopped. So, we’ll let you enslave all of Eastern Europe as long as you let your kids get killed instead of ours. After all, we have a terrible unemployment problem in the US and a Depression, and the best way to solve that would be to kill off a half a million of our least employable young people whilst creating a military-industrial complex that will employ millions from here to eternity.”
For that outcome, FDR is viewed as one of the greatest presidents ever. Go figure.
That said, the US contributions to winning WW2 were consequential; Hitler was pinned between two fronts, but that statement assumes that both fronts were threatening.
But, when it comes to consequential losses, Russia’s were even more so, in terms of blood and money.