The difference between except and and expect (to which you refer below) would make all the difference in one sense and be startlingly corroborative in another.

Your wording is awkward. I think that you mean, "How many people have to believe a lie before it is widely perceived as truth?"

66% of #Republicons still believe Trump won, Biden lost, and the #Democrats, out of power, somehow stole the election. 33% of #Americans still won't get #Vaccinated. i think the number is 33%. or, #Minority Rule.

I think you mean “accepted”, rather than “expected”. The answer is one. The more important question would be, “how many people have to believe a lie before it is dangerous”?