This is all opinion and I may be misinformed, so take it with a grain of salt.
It is really sad when you think about how the beginning of the new millennium seemed an optimistic time in Russia when the economy was starting to pick up—albeit mostly in the wealthier western cities—but then Crimea happens and the recovery stalls under global sanctions. He should've got the message at that point, but no. He's such a cold warrior. He can't see any way for Russia to grow other than through conquest and putting in puppet governments everywhere.
And the worst part is now, he has no incentive to end this war. It's the only thing that's keeping him alive. Ending it would be political suicide, and failed leaders tend to have a very short life expectancy. So he's all paranoid and bunkered up. Actually, not even paranoid. He really does have reason to fear for his life.