Putin was so sure we wouldn't do anything (after gobbling up Crimea with next to no repercussions) he was comfortable enough to leave close to 20% of a year's gdp parked in Western banks, including European banks, as Russia invaded a European country.
He rightfully judged Europe's Eloi wouldn't go to war over Ukraine, but that left the most obvious move in the world for the West to play - sanctions. Russia practically deserves to lose the money for Putin being so moronic. Russia's reserves were parked elsewhere too, so it's not like he didn't have options.
Oops. Fortunately for him he's a dictator and can kill anyone who looks at him funny domestically. Leaving the reserves in the West's lap wasn't even his worst miscalculation in operation show the satellite country who's the boss.
