What “expectations” Did the lefties really delude themselves that much?
Yes, big time. If you read any comments sections of articles, or response to tweets there are many "you just wait until Mueller unloads on Trump" or such. They really expect Trump to be perp walked &/or impeached.
If/when nothing comes from this sham investigation, there will be conspiracy theories that Trump paid him off or some other BS,. That Trump is really guilty but somebody got to Mueller. They will never accept anything short of a lynching.
Of course, there’s no way Trump could have beaten Hillary without an act of God or criminal conspiracy...