We've been over the reasons why - you just refuse to entertain any other scenario than the (neocon) official US government narrative (bad Russians bent on world domination). But you and I both know because Putin told us why:
Ukraine is another matter. Russia regards its inclusion in NATO as an existential threat. Putin stated on the eve of the invasion on February 23:
Positioning areas for interceptor missiles are being established in Romania and Poland as part of the US project to create a global missile defense system. It is common knowledge that the launchers deployed there can be used for Tomahawk cruise missiles—offensive strike systems.
In addition, the United States is developing its all-purpose Standard Missile-6, which can provide air and missile defense, as well as strike ground and surface targets. In other words, the allegedly defensive US missile defense system is developing and expanding its new offensive capabilities.
The information we have gives us good reason to believe that Ukraine’s accession to NATO and the subsequent deployment of NATO facilities has already been decided and is only a matter of time. We clearly understand that given this scenario, the level of military threats to Russia will increase dramatically, several times over. And I would like to emphasize at this point that the risk of a sudden strike at our country will multiply.
As the Ukraine war enters its twelfth month, the military situation remains a stalemate, but a stalemate that gives the political advantage to Russia. If Russia can hold most of the territory in the oblasts of Luhansk, Donetsk, Zaporizhzhia, and Kherson that it annexed on Sept. 30, 2022, it will...
Clearly he thought having Ukraine in NATO would constitute an existential threat to Russia. According to Putin it was the rough equivalent of Soviet nukes in Cuba. If we took that off the table, Russia would in all likelihood withdraw. So that is not, in fact, what you "want" - you want regime change in Russia, like all neocons. And when it happens and the world becomes even less safe, you will find some other "evil dictator" to blame, rather than look in the mirror where the real culprit resides.