Clear thinking and rational? Maybe, but he completely underestimated Ukraine's willingness to resist, Europe's resolve to help Ukraine and overestimated his military capabilities. If he was running a company, he would have sent it bankrupt by now. Part of Putin's problem is his isolation. He is out of touch with reality. This happens to a lot of dictators. Hitler was committing divisions that did not exist to Germany's defence. That is not the mark of a rational being. No doubt Putin was rational at one time. Now he believes his own propaganda. It's pathetic and tragic. The human cost on both sides of the border is immense, as is the cost of waging this war. Putin will answer to God for his unjustified treatment of Ukraine and also his own troops. I would not like to be in his shoes on that day.
This assumes you understand Putin's overall goal, which you don't.
Also comparing Putin to Hitler is not in any way comforting. Yes, Hitler was irrational, but that became obvious after he had burned down most of the Eurasian continent.
I think that like Sun Tzu taught, you don't underestimate your enemy. So if I give Putin respect and assume that what has happened is what he anticipate would happen it results in a very different interpretation to the facts.
NATO and the US had displayed a pattern of expanding into the USSR's former region ever since the collapse of the USSR and finally they had crossed a red line by trying to get Ukraine to join NATO. 20 million died in Ukraine in the last WW, and it was the highway into Russia that Germany used. It is every easy to roll through Ukraine rather than the mountain range to the north. So it is not absurd that Russia would think that Ukraine is essential to their national defense. At the very least talk of Ukraine joining NATO violated the treaty they had with Ukraine when it sought independence. Now if Putin is a logical, reasonable person who has carefully weighed the evidence he would have to to consider that this expansion of NATO was not an oversight or accidental but rather intentional. Therefore when they invaded Ukraine they had to know that this could result in a war with Ukraine and the USA. They also must know that their economy is a very small percent of the economies of the US and EU and so the idea of fighting a war against Ukraine + NATO + the US would not work out if it was conventional.
Still if I felt I had been backed into a corner and it was fight or die I would do the best I could which would include making an alliance with China, Iran, and North Korea (which can arguably be seen as a fact). I would also realize that the only chance I have at winning this war would be to take out the US and the only way I can do that is with a surprise nuclear attack. Now you would have to justify such an attack with the rest of the world, that would mean top military and political leaders would have to clearly and expressly warn the US of a possible nuclear attack (they have done that), they would need to get out of nuclear treaties (they have done that), they would need to have a weapon that could evade our defenses (they do have such a weapon), I'd put that weapon 5 minutes off the US coastline (they are on a destroyer off the coast of Bermuda, they travel at mach 6 and could be in Washington DC in 5 minutes), we also believe that their submarines are parked off our East and West coast. Now you don't fire nuclear missiles at the US without being absolutely sure they will work, so in the last few days they ran a drill with those Zircon missiles in which they jammed our radar, cellular and internet for 34 seconds. But even with all that you would still expect compelling evidence for why this was necessary. Russia is claiming they have evidence that the US used bioweapons labs in Ukraine to commit crimes against humanity, after a worldwide pandemic linked to the US and a vaccine that is looking like a kill shot the world will definitely see this as a valid reason if Russia has the evidence.