My reasoning here is as follows:

Putin doesn't care about money - he has all the money he needs. He doesn't also care about welfare of average Russian citizens as long as he can stay within power.

He cares mostly about staying in power and by extension about others perceiving him as a good leader. It is incredibly obvious to me that dictators don't end well when they lose their power. I assume losing power is as bad outcome for Putin, game-theoretically as getting Russia nuked to the ground.

Over the last 30 years Russia was progressively losing ground within its' sphere of influence. Poland, Ukraine even Belarus are slowly fading further and further away. All the context for today we need is the Orange Revolution, Euromaidan and recent protests in Belarus which show high level of anti-russian and pro-western sentiment among society of these countries.

When those countries turn fully pro-western, with relatively wealthier and happier citizenry, it's a matter of days rather than years when the same sentiments will reach Russia, leading to a quick change in Russia's top-level government.

If Putin wants to stay in power, he must convince people in Ukraine and Belarus that it's in their best interest to stay on his side. And lethal force is really the only tool he has at his disposal for it.

So his options really are:
- Hope that he can cling to some remaining bits of power until a reasonably peaceful end of life and be aware that probably soon afterwards Russia will start turning pro-democratic.
- Do whatever is within his control to keep Ukraine and Belarus subdued.

Weighing pros and cons in this particularly hard situation, he must have chosen that option number two has a higher EV to keep him in power for longer. What can happen now:

- (best scenario for the democratic world) Ukrainian forces manage to defend themselves from the offensive. That basically means Russia's collapse as it is today. It's probably in the best interest of many western democracies to maximize the probability of this outcome, but I'm not sure how probable it is really.

- (worst scenario for the democratic world) Ukraine is taken over completely very quickly with minimal Russian cost and loss. World doesn't really have a chance to react. Russia weathers sanctions ok and gets into closer ties with China.

- Russia cripples Ukraine military, the war drags on guerilla-style. Russia manages to successfully occupy part of the country and the rest becomes warzone wasteland. Russia saves face, Ukraine and Belarus and under complete control.

- War drags on and Russian can't continue with the cost of it. Ukraine gets severely weakened but manages some resemblance of independence while Russia occupies only very minor territories. May be enough for Russia to save face, but I would bet not really and it would lead to another scenario where Russian government collapses.

- Western allies get involved in the conflict, but none of the sides decide to use nukes. Russian military will get destroyed and Russian government collapses.

- (worst scenario for the whole world) Western allies get involved in the conflict, and one of the sides decide to use nukes. Humanity's development gets moved back hundreds of years.

- China and Russia are in active cooperation. Russia will keep escalating the war in Europe until one or all western nations engages. On that day China begins offensive on Taiwan and attacks US. WW3 starts.

I believe in most of the countries in the world military command is playing out all of those and many more potential scenarios. I would like to live in more boring times.