[xpl]

Yes, that is a plausible explanation.

On the other hand, I have witnessed how the Putin's rhetoric made a U-turn over those dozens of years — from "Fukuyama-level" liberal and pro-Western (early Putin), to "geopolitical realist" and pretty much anti-Western (as of today).

I don't know how much this reflects his actual worldview transformation (if there was any), but I have reasons to believe that there is no smoke without fire.

[partiallypro]

I highly encourage you to read some well researched books about Putin, his world view hasn't changed all that much. This is a former KGB man. He has held, for a while, that the fall of the USSR was one of the biggest disasters in history. His rise in power was stemmed by a terrorist attack which he possibly had a hand in to orchestrate his rise and the eventual invasion of Chechnya.