The handwriting was on the wall. Russia amassed 200,000 troops on the Russian and Belarusian borders of Ukraine. Putin had been trash talking against Ukraine for months before the "exercises". Yet Zelensky and his administration did not mobilize their full military, call up their reserves, or set up a civilian militia. He should have gotten weapons and funds from NATO months ago.
Ukrainian lack of diligence does not excuse the Russian invasion by any means. Nevertheless, the Ukrainian government was negligent, and their country is paying the price.
Maybe, but Ukraine wasn’t offered any help before it was too late either. As you said, the writing was on the wall.