>>23507
>"we can build socialism in one country"
But not that was happened. First they got the Baltics, part of Romania, Poland, tried Finaland. Later got half of Europe. Even Yugo became communist. Then China, North Korea. The whole Cold War was about turning third world into communist.
>losing territory
That was the strategy for Russia for centuries. They weren't queasy losing masses of people, they done that in peace too, supposing they were feared to lose land (what would be recaptured anyway - overconfidence can whisper that in their ears too) isn't reasonable.
>Would anyone invest in so much tanks if they had old-style trench warfare in mind?
No, they had attack in mind. This is why Soviet had about five times more tanks than the Germans.

>Soviets thought that mechanization is the future, offensive or defensive, doesn't matter.
The 9. point about Obsolecence is partly about this question. After the German attack mechanized corps were disbanded. Because they were useless for them in defense, they become obsolete with the Barbarossa.
>Reality proved that it isn't true, and BT wasn't good at all, but who would know this before big war?
BT was tried at Kalkhin-Gol and it wasn't good on terrain. It was supposed to be use on paved roads, what the west didn't lack.
>T-34 [...] wasn't that good.
That's relative. Compared to German tanks it was fine.
>enough roads
Maybe railways. Even on freshly liberated countries there wasn't enough. Favors defense. It only needed minefields, anti-tank trenches and such. But they didn't constructed such things. With the lead of Zhukov they reinforced bridges and built many kms of roads and railway - exactly to help transport troops to west for an offensive.
>airplains