But I won't dismiss that he is just a complete nut and the whole take overs gone tits up
That is more the scenario. Imo.
The Ukraine is regaining a massive amount of territory atm, thanks to the assistance from The West.
Ukraine becoming a part of NATO wasn't ever a threat to Russia. The west just doesn't invade countries for the sake of gaining strategic advantage. Not in this day and age anyway. The west prefers democracy, peace and stability.
Putin is a nutcase. The sooner he leaves this world, the better.
Problem is that he will probably be replaced by another nutcase.
I have the utmost respect for Zelensky and what he has tried to do for Ukraine.
Unfortunately, he will probably end up being another Mickael Gorbachev. A peacemaker in his time but ultimately overthrown by another nutcase.