It did not help matters that Stalin invaded Finland in 1939 with a million and a half men, and four months later, the half-million survivors went home licking their wounds.
Hitler saw what Finland's puny Army and reservists had done to Stalin's Red Army and considered what his own blooded professionals could do. He miscalculated; The Soviets had learned to use the Winter weather from the Finns.
and from the war with Napoleon.
His time time would have been better spent studying map reading and military history rather than painting watercolors.
The Finn's motti tactics were a modern version of Arminius' Teuteburg Forest campaign in which the Roman educated German Arminius completely annihilated three Roman Legions led by the lawyer Varus. Heavily wooded areas bound by swamp and marshland prevented maneuver in both cases. And the three thousand km. plus Eastern Front on a map dwarfs the Karelian peninsula....just my two pfennigs or kopeks. ;>)