Putin (et al.) has already proven to be stupid : the invasion of Ukraine was going quite well for him since 2014, he could have continued salami slicing it while the EU was still mostly asleep (and not willing to make a fuss as a Russian hydrocarbons importer).

But no, he went for a 'quick' victory instead, and ended up bogged in a much higher intensity war, made the Russian military a laughing stock, and kicked the EU/Nato bees nest so hard that another 2 countries immediately joined NATO.