Of course that's not true. Nations can run out of at least three things required to wage war: resources, people, or will.
And the Soviets were nowhere near running out of resources or people at the end of the Winter War, as shown by their ability to defeat a much more powerful enemy a few years later.
Yes, we all know Nazi Germany was only fighting against the Soviets between '40-'45. Truly, the use of U.S. and U.K. bombers that incapacitated Berlin's war machinery production never happened. The western side of the war was dealt with promptly, leaving only in the east, the Soviets to repent the Nazis.
It was the pure will of the Soviets which led them to their, and only their victory.
I don't even know what to say. It must have been a lack of will, surely. /s
(edit)
Look, I know what you're trying to say. But if we put it that way, we're implying that they could've surpassed the will of the Finns in some way, if they wanted to. And I firmly believe that to not have been the case.
The Soviets bore the brunt of the fight against Germany. Roughly two-thirds of German casualties were on the Eastern Front, and the Soviets killed or captured about 9 million Axis soldiers, more than double the entire population of Finland in 1940.
You know you're taking out of the equation the will of the Finns to defend their country. You keep talking as if the Soviets could've done it, if they wanted to.
They didn't do it, and you know why? Because they tried, and couldn't. That's what happened.
I'm sure you mean well, but even though they killed more than 5.5 million Nazis, they couldn't kill more than 70k Finns. And that's history, not some alternative possibility.