As it relates to WWIII...
Many world leaders aren't in power because they are smarter or stronger than everyone else. They simply learn how to play the game in order to get into the position of power they want. But then they often have to lie, cheat, and steal(elections) in order to stay there.
In the world of politics, it's about what people believe. You can make people believe almost anything. It's not as hard as you think. It's also not as easy as Mel imagines because he thinks we're all stupid because we're black. That's not true. However, it is true that even well-meaning black people can fall prey to conspiracy theories and propaganda used to push forward the agenda of white supremacy; and to protect its gains.
Trump showed that he was also susceptible to conspiracy theories... because, in his case, he's stupid. He's stupid because he's never really been forced to live in a world in which he had to be smart. His family's wealth created that environment. He surrounds himself with smarter people who make decisions for him and advises him on what decisions he should make, all for the purpose of gaining more wealth and maintaining the image of the smart businessman.
Putin is similar but not nearly as stupid. Putin is cunning, politically, but he's not a super spy even though he was in the KGB. He was using propaganda in order to support his invasion of Ukraine as if Ukrainians are being held hostage by neo-nazis who are Western puppets. He would much rather Ukraine be run by a puppet under his own control. But he thought Ukrainians would believe and welcome him.
But part of this belief is disassociated from reality. To be a world leader you have to believe in yourself with a high degree of confidence. But if you cannot guard against your own power you will fall victim to corruption. And eventually, you can start believing your own hype. And that's when you stop listening to your advisors; the people who tried to tell you that invading Ukraine would be a mistake. Once you stop listening to the people whose job it is to maintain your image of competence... things like this happen.
Putin has lost because he could not control the narrative. He was emboldened by Trump because Trump was willing to lend credibility to the Russian narrative and back up anything Putin said; thus leveraging the credibility of the United States itself. And then that same credibility plays against Biden, allowing many Conservatives to still back Putin over the United States government (ie Tucker Carlson). Trump already proved with Ukraine, when he asked for a favor in return, that he was only willing to go out of his way like that if his back was getting scratched. Therefore, Trump sold out American credibility for his own assets and business prospects in Russia. Biden doesn't personally benefit from Russia though and therefore he and other world leaders are willing to sanction Russia economically.
This isn't about WWIII. This is about money. Trump wasn't able to undo all the previous sanctions against Putin and his personal assets. But Putin's oligarchs were still able to move money. If Putin conquers other countries then he can tax them. The Russian economy is weak as hell. Even though Putin might be wealthy personally, Russia is not. Therefore, his status, in terms of global power, has been threatened for a while now. And guess what? If you are broke then you cannot maintain your military. Or your weapons. Military size is often large enough to enable conquest. If you're not using conquest to gain more resources then the size of your military works against you because you have to pay them with your government's revenues. But if your GDP is low and weakening then your whole infrastructure weakens. And even if you shrink your military (leaving your defense low enough to be conquered yourself) would the already difficult job market be able to absorb all those soldiers looking for work?
He might even have to borrow money from other countries, which means he would owe even more. It already owes about $140 Billion dollars. Russia is getting its credit rating downgraded which not only affects its ability to borrow and at what interest rate, but consider the value of Russia's own currency and how that could tank. When your currency falls in relation to the US dollar... that has huge implications. It means that every Russian would automatically have less money even if they have the same amount of money in the bank. Because of inflation and the cost of foreign goods and services. Ouch.
War is expensive; extremely so. Putin cannot afford to fight WWIII. He can threaten nukes, of course, but he also doesn't know all the countermeasures that have been created over the years because America has long since considered Russia a threat and many defense programs are kept top secret for this reason. Checks and balances. Putin knows no one wants WWIII so he can threaten that if he's that desperate. However, it's kind of like North Korea testing weapons while their people live in poverty. Isolating yourself from the world isn't winning and it is only because these megalomaniacs stop listening and surround themselves with yes men too afraid, to be honest, that they think these are good chess moves. But these sanctions will test Putin and ultimately call his bluff.
And ultimately, he will probably fold.
Because Putin is also not suicidal. Listen to the oligarchs. People are loyal to money. Without the oligarchs, Putin doesn't really have the people. And without their support, the Russian military will seize power. They are likely already thinking about it and waiting to see if Putin listens to the oligarchs who would very much like to continue increasing, not losing, their sizable fortunes. Putin is most likely just waiting for an excuse to pull out or make some deal with Zelensky that makes it seem like he wasn't weak for pulling out. Because if Putin looks weak then he knows that's a bad position to be in when he's already unpopular. A weak dictator is often a dead dictator.