It's not just about now. Who knows what happens in the future.
Eastern Europe was fractured and weak following World War One. A huge invasion still came twenty years later. This is a game played out in centuries, not 20 years. The future is unpredictable. Russians leaders plan in that world.
If I can read Putin's mind, if you're a respected leader, your citizens will probably be ready to let you stay in power, and in the event of an attack, to die for you, but if you're a corrupt grifting piece of shit, then, first the walls to your bedroom better be thick, next would be the walls to the Kremlin, and finally the walls around your country's borders, and then even beyond.
My guess is why Putin hates the "NATO sphere of influence" is that he doesn't like democracy, because democracy means his head will end up on a noose, or in the best case scenario, in prison with his wealth taken from him. But on the flip side, it's not like American or EU democracy is free of thieves and nepotism either. Special greetings to Jean-Claude Juncker and Ursula von der Leyen!
I think if NATO backed Lithuanian agents hadnt tried to foment an independence movement in Kaliningrad then Russia might feel a little more confident that NATO's long term goal wasnt the Balkanization of Russia.
If Russia does get trounced in this war and Ukraine joins NATO I would expect suspiciously well funded independence movements to start popping up in Russia. This conflict wont stop at their borders.
It'll stop and we'll finally lose interest when Russia breaks into 16 different poverty stricken polities.
Eastern Europe was fractured and weak following World War One. A huge invasion still came twenty years later. This is a game played out in centuries, not 20 years. The future is unpredictable. Russians leaders plan in that world.