LT42 in the run up to the invasion, I sat on a lot of calls in which some pretty big names (intelligence services, senior US political figures) all scoffed at the idea Putin would invade or that his ambitions extended beyond Lunansk and Donetsk because it just didn’t make sense. So yes, the general conclusion of most experts was clearly that he was bloody bonkers.
You can retrospectively try and fit a story to Putin’s motives if you like (and you ARE doing!), but it still takes an unhinged mind to do what he’s doing. And yes fucking around with countries on its border and attempting Russification IS exactly what Russia has done for centuries, just as throwing Russian lives into the meat grinder is exactly what the likes of Stalin have done in the past.