That Russia was supposed to "rollover Ukraine" is a false premise started by western politicians and journalists to make the Russians appear to be weak and the Ukrainians appear to be strong. Russia invaded with just 40,000 soldiers. Not a tenth of whats needed to conquer a country. They weren't trying to conquer the country. Just move into the Donetsk People's Republic and the Luhansk People's Republic, which they have occupied since the beginning of the war. The Russians were obviously trying to show they were serious and thought a peace deal would be struck. But western globalists want war.