...Nnnno, I'm pretty sure it's easier to dupe one person than a group of people each with their own way of thinking.
I do believe it takes just 4 people in a group for individuals to start going along with the rest of the group. It might be the research into the groupthink thing that found that...
Basically the experiment was a group of three confederates (folk working with the researcher, but ostensibly part of the experiment) and one subject. They were given a decision to make, and the three confederates generally agreed to the most sub-optimal thing, which the subject went along with.
They did find, though, that if one of the confederate a raised an issue with the decision (usually that it was a shit decision) then that gave the subject more confidence to actually come out and say what they were thinking.