Why did the west spend more money on Ukraine’s defense budget during this war than Ukraine itself ever has since it’s existence, despite Ukraine not being a NATO member? Is there any precedence in this.

Why shouldn’t Putin just nuke Kiev in a decapitation strike, win the war, and see if the west is fucking stupid enough to respond in kind for a none NATO country? Sounds better than Russian letting itself collapse as a country midst of growing inner-resentment and opposition, where propagandists are admitting this war is a failure.