Not that I'm an expert on this topic, but my guess is that Putin lives in a self-produced information bubble. He's superficially well-informed but relies way to

Not that I'm an expert on this topic, but my guess is that Putin lives in a self-produced information bubble. He's superficially well-informed but relies way too much on intelligence reports, which can completely misrepresent what's going on when you look at them in isolation. His mindeset is "me against others" and "Russia against the rest of the world." He is surrounded by Yes-sayers as advisers and some oligarch friends who are probably also not particularly connected with reality and more interested in real estate, superyachts and Gazprom stocks. Lack of good advisers is a huge problem. Given this background and a certain lack of empathy and sense of right and wrong, from Putin's perspective the past actions appear reasonable. He successfully prevented Ukraine from joining NATO and the EU and involved it into a useless war in the Donbas region. Now things weren't moving on from this point and the situation in the Donbas region was a constant source of concern. So he apparently decided to "solve" the Donbas problem once and for all, perhaps as part of his legacy, and miscalculated. From a pure military perspective the decision might seem reasonable. Ukraine's military is badly outnumbered and still has not much of a chance in the long run. He probably thought it's going to be a quick rush into the capital, installing a puppet regime, and he's done. Western military analysts thought the same. Why he's been so extremely fixed on keeping Ukraine out of NATO can probably only be explained with his KGB background and the corresponding mindset. There are superficial justifications, it is a prima facie reasonable standpoint of Russia to be against this, but nevertheless Putin seems to be fixated on this in an abnormal way. It is clear that NATO membership of Ukraine would not pose a threat to Russia. However, you could just as well ask why Putin hasn't diversified Russia's economy, made the country a close ally and trade partner of the EU, and helped turning mother Russia into a prospering modern democratic state. This wouldn't have been hard, Russia has all the potential you could imagine - rich of resources, longstanding integration into Europe, excellent scientists and engineers (before the brain drain). The answer is probably that Putin is a paranoid poison murderer and filthy rich ex-KGB officer who came to power more or less by accident. He's simply not good presidential material. Normally this isn't a problem (most presidents aren't), but when a "president" becomes a dictator and is surrounded by Yes-sayers in an information bubble it certainly is a problem.