Putin thinks there is an upside - It will deter west from integrating Ukraine into NATO. In a way this makes sense. West just don't want to deal with a Russian headache like this.
If you say a lot, then the ROI can be very high.
Russia formally has a new Stalin, a new Tsar, whatever you want to title him with. And the world should act accordingly. Putin will have to kill a lot of people domestically from here on out if he's moving into Empire mode, because the situation will get messy very fast and there will be real domestic opposition and he'll strongly dislike that.
Russia is a leper again.
And besides this, we should be defending the new, fragile democracy in Ukraine, on a moral basis. They're our friends and they want our help.
When your friend or relative comes back in a pine box, do you want to know it was just another bad decision with nothing good coming of that sacrifice?
That said, I think the US has options here. We don't need to "occupy" Ukraine as they have plenty of troops. What they need is air superiority.
We should consider establishing a no-fly zone around all of Ukraine (and maybe Crimea). The risk to American lives would be as minimal as possible while still severely restraining Russia's ability to wage war..
But ROI is all I can see that actually drives the US these days - why do you think the phrase "run the government like a business" is so ingrained? Personally, I'd prefer to run the government like a government, but I'm just one voter out of what... 150 million or so?