I don't know if it was the dumbest take, because let's not forget that there were some people predicting Trump to win California.
I remember some folks predicting that mail-ballot tampering would turn New Jersey & New York into tossups
I'm talking about widespread takes. Although one that's arguably even dumber than this one that's fairly widespread is the notion that Trump actually came close to overturning the election results after the election, which is pretty laughable. (and not the storming of the Capitol did not even come remotely close to overturning the election results.)