They won’t be voting but the left will be voting for them. They had the joke of vote early and often back in 2008/9. They expanded that to a complete system, all while the GOP slept. 2016 was an anomaly that they took care of in 2020 with the help of a man made virus and tyranny.
Obama was popular. No need for fraud.
They were overconfident in 2016. They were stuck in their echo chamber. So they didn't think they needed to cheat.