I suspect that's a gamble too far for Putin. Invading Ukraine is incredibly costly, but there is little spillover risk, and there's an underexplored side benefit here: Belarus, which has long been a Russian client state, is now going to be housing Russian troops indefinitely, its military has effectively been placed in Russian hands, and the country will probably be more-or-less peaceably annexed whenever Lukashenko dies/retires. Invading the Baltics, much though he would like to, triggers Article V; unless NATO outright disbands, it means direct conflict between Russia and NATO, and that's a conflict that Russia doesn't win (it's likely a conflict that absolutely no one wins, but I have no idea what Russia's win condition is there).