Then my explanation probably does not apply to you, at least in this specific topic. There are other ways people can get strong opinions on something, for example by having a personal experience, or by analogy with something else they already have strong opinions about (based on what you wrote, this would be my guess).

But I think that in a situation like FiftyTwo described, an average person who would happen to have their best friend(s) on one side of the topic, would most likely join them without hesitation.