It's not a question of blame it's a question of working in your own self interest. Next election you have 3 choices basically. First you can make things dramatically worse by voting Trump and pushing us even closer to the fascist dictatorship we're already edging towards. Second you could vote Biden which while not really improving anything at least buys 4 more years for the GOP to continue its slow death. Third you can abstain by either not voting or voting for anybody else which dramatically hurts Biden and helps Trump because those voting for Trump aren't the ones abstaining. Sure maybe it will send a message to the DNC, although history seems to show it won't, but in the meantime you've just helped Cheeto Mussolini come into power and if you're someone who would be considered liberal there's a decent chance that's going to get you killed or at least persecuted in the near future.