Because short term survival means surrender, followed by the medium term getting conscripted by Putin as cannon fodder to go after the next country.
Is it not just speculation? Does it have any merits? Would he do it? What makes you think that it is going to happen, that he wants to do it? Could he actually attempt to do it?
Having already done it three times:
1. https://en.wikipedia.org/wiki/Second_Chechen_War
2. https://en.wikipedia.org/wiki/Russo-Georgian_War
3. https://www.hrw.org/news/2023/12/20/russia-forces-ukrainians...
What is currently limiting him from going further is, specifically, the armed forces of Ukraine.
I am referring to NATO, UN, ICC, Amnesty International & Human Rights Organizations, global backslash, fear of uncontrollable consequences (wrt. current allies like China and India, as they are Russia's key trade partners).
So there are those deterrents: legal charges, sanctions, political pressure, military retaliation, geopolitical fallout, and internal resistance within Russia itself.
Even Russian oligarchs and elites might resist, fearing total international isolation.
There are many reasons to not be afraid of what we might believe Putin would do ("getting conscripted by Putin as cannon fodder to go after the next country" and so forth).
NATO only applies if they go specifically for a NATO country — which is why Ukraine wants into NATO in the first place, and why the invasion of Ukraine got Finland to join in a hurry. Also this is only a risk while NATO continues to still exist, which is threatened both because Trump has explicitly said: https://www.bbc.com/news/world-us-canada-68266447
And: https://apnews.com/article/trump-biden-offshore-drilling-gul...
And: https://www.ctvnews.ca/politics/article/former-australian-pm...
But also Russia is starting to prepare for direct NATO confrontation anyway: https://www.reuters.com/world/europe/putin-accuses-west-push...
> UN
Russia is on the permanent security council, they have a veto: https://en.wikipedia.org/wiki/Permanent_members_of_the_Unite...
> ICC
Already has arrest warrants for them, can't escalate further: https://en.wikipedia.org/wiki/International_Criminal_Court_a...
> Amnesty International & Human Rights Organizations, global backslash, fear of uncontrollable consequences (wrt. current allies like China and India, they are Russia's key trade partners).
None of this stopped them so far, why would it start?
Especially on trade: Russia is a petrostate, their main export is fuel, the invasion of Ukraine by itself sped up the European transition away from fossil fuels in general and their fossil fuels in particular, and everyone Russia does business with — including "allies", though that's too strong a word for their relationship with India — has every reason to take advantage of the price ceiling to get discounts even when they don't explicitly take part in the actual ceiling itself: https://en.wikipedia.org/wiki/2022_Russian_crude_oil_price_c...
> There are many reasons to not be afraid of what we might believe Putin would do ("getting conscripted by Putin as cannon fodder to go after the next country" and so forth).
Why are you ignoring the evidence that this has already happened three times?
Why do you insist on treating this as a hypothetical?