Occam's Razor tells us that the Russians acted to 1) stop the constant bombing and cultural suppression of the Russian speaking people in the east and south of Ukraine that had been ongoing since the US backed coup in 2014 and 2) to finally move against the build up of forces and weapons that the US had been pouring into Ukraine since the coup to trigger a war on Russia's border that they hoped would lead to the destruction and dismemberment of the Russian state itself (the openly stated goals of the US).

(In parenthesis, I will also note the very silly but oft-repeated mistake of conflating Putin with Russia in the comment above. Russia does not act on the whims or personal ambitions of Putin; indeed, Putin stays in power largely by responding to the needs and desires of the Russian people, and the pressure inside Russia for him to act against the existential threat building on the Russian/Ukrainian border has been very strong and he has faced criticism for not acting earlier.)

Occam's razor is the idea that, in trying to understand something, getting unnecessary information out of the way is the fastest way to the truth or to the best explanation (c) wiki

The explanation about dictator's desire for power(now also life) is more simple than geopolitics and cultural suppression.

And about the needs of the Russian people: I don't remember Russians having a debate about starting a full scale war. Maybe Putin thinks its what they need but if there was a real debate we can safely assume people would prioritize having in-house toilets and a million other things that are suddenly became not so important.

You are 'applying Occam's razor' to a fiction, not reality. Anyone can dream up a fiction (or take one supplied to them) and then draw a simplistic conclusion from it.

I'm applying explanation to a fact. "Fiction" is not the right property to categorize explanations, the right one would be "probability". So yes, anyone can dream up an explanation and then judge if one is more probable than the other.