It’s actually not. 60% opposed,+20% not sure is 80% of the population would count as a “vast majority”
https://today.yougov.com/politics/articles/53787-scant-ameri...
https://today.yougov.com/politics/articles/53787-scant-ameri...
This does not apply to opinion questions that show huge differences (not single digit percentage point differences), though there validity, not reliability is a bigger concern, especially since there exists no voting benchmark you can measure against.
Still: I think it’s awfully convenient to just wholly discount actual empirical evidence whenever you feel like it because it might not be perfect. Why exactly do you think your gut feeling is better?