I thought that Putin was bluffing, based on the low number of the soldiers around the borders alone. 200 000 simply aren't enough to take a country the size of Ukraine. During the wars of the 20th century, the Ukrainian theatre was regularly contested by millions of soldiers at the same time, and basic control of population still requires about 1 soldier to approx. 30 civilians or so, even if the only resistance is guerilla-like. It is much worse with the regular army fighting back.
As we saw, 200 000 definitely weren't enough to take Ukraine, but possibly Putin believed that the country was going to collapse immediately instead of fighting back.
The number of troops was absolutely low. My read at the time was that 100,000 troops (the early build-up) was concerning but could easily be a bluff or a test. The naval movement was the tip off to me, with the blood reserves setting a very short clock on how soon it would start.
I really think the Russians believed they either were going to be welcomed by many Ukrainians, or that a blitz for Kiev would be a quick 3-7 day affair. The downed planes of paratroopers in the first day or two, plus the convoy of trucks that only brought a few days of diesel seem to line up with the second scenario.
As we saw, 200 000 definitely weren't enough to take Ukraine, but possibly Putin believed that the country was going to collapse immediately instead of fighting back.