Putin's thinking was that NATO couldn't admit Ukraine if Ukraine was at war with Russia because that would immediately put NATO at war with Russia. And so by attacking Ukraine they prevented Ukraine from joining NATO.  I'm sure Putin did not expect as much Western backing as Ukraine has gotten.  But even with that Western backing, Ukraine is still not in NATO and NATO is still not at direct war with Russia.  So we don't have a decisive answer as to whether Putin's strategy "screwed himself" or not, we have to wait for the future to show us who is the better strategist, Vladimir Putin or karnage.