I used to think the same as you. Why doesn't Russia see the threat to itself from China and Iran? But I think the answer is that Russia is not a part of Europe. It is more Asiatic than European. And to the Slovophiles, Russia is a unique continent to itself, neither a part of Europe nor Asia.
In the 3rd centure AD, the Roman emperor Constantine moved the capital from Rome to Constantinople in the more prosperous east of the empire. Constantinople became the New or Second Rome. That Second Rome converted the Russians to Eastern Orthodox Christianity. When Constantinople fell to the Turks in the 15th century, Moscow thought that it was now the Third Rome. Even the ruling family took the name Romanoff.
Russia has a long history of ruling an empire under a Tsar. (This word Tsar derives from the Latin Caesar via the German Kaiser.) Many Russians still think that it is their destiny to rule a great empire. The Soviet Union was only the last version of that empire. Putin is simply trying to revive the Russian empire.
Indeed. Russia is acting like Russia again, not like the USSR.
And we have foolishly forgotten that. Russia always fights when a great power projects influence on her borders. They are to paranoid for that.