Because he sees himself as the successor of previous emperors of Russia such as Nicholas I. To him, Gorbachev was just a fake leader, watching over disaster and dissolution, while he's a monarchical figure of inevitable destiny.

He sees the invasion of Ukraine as a defensive war, trying to keep the empire together. Prior to 2014, the Ukrainian government was essentially a puppet to Russia, after that it was like another piece of the empire was "taken".

I recommend listening to Vlad Vexler to get an insight into how the tyrant thinks. His chat channel is also great.