Perhaps Putin's action isn't as irrational as it seems?
How so? Russia already controlled the whole of Crimea since 2014. Ukraine joining NATO would certainly NOT have changed the status of Crimea.
Putin's action would have been rational if he had captured Kyiv in a couple of days or weeks, and managed to install a puppet government. IMO the whole thing was based on bad intel, lies, corruption and yes-men who told their superiors what they want to hear, rather than what was the truth about Ukraine's defense capabilities. After that Putin couldn't back off without losing his face, and obviously loss of human lives and economic damage mean nothing compared to that to him.