The thing is (and I said this before), history is FILLED with smart people who make fatal mistakes. Putin is no idiot. He's evil imo, but not dumb. But some (ahem...
@Da Speeit ) think that because he's been a shrewd leader up until now that we have to assume every decision he makes is going to work out for him.
I'm actually skeptical that the Ukrainians can hold out a ton longer. I think the writing is mostly on the wall in terms of this war. But that doesn't mean Putin is playing 4d chess. In this case, I think he looks like the shortsighted one that's coloring with crayons while the west is looking at him and saying "You're really doing this huh? You REALLY didn't think we can tank your economy? Uhh...okay...sorry about what's coming up..."
Unfortunately, both the Ukrainian and Russian people pay the price. It might honestly be better for the Ukrainians to negotiate some sort of surrender at this point. It's hard to convince people not to fight for their home (especially after what's happening lately with civilian centers being hit). But to get this over now and just let the insurgency begin. And (like you said) let the sanctions really squeeze Russia to where **maybe** the internal pressure finally ends Putin.