When people get polled, they are more likely to lie. Even more if your side of the votes gets hates about being racist and such. When my part tried independance, the leave part last time lost with 49%. The polls were saying leaving would lose with 30%. Because leaving was shamed as being hateful, fear mongered into possibility of hostility and economic shame. Its the same rethoric used in every single referedum for independance. The world is ending for the people that want to stay, hence they shame people and it skew polls where you speak to another human. Once you are alone with a piece of paper or a computer screen, your conviction comes back.