It's got nothing to do with disagreeing with me. People who thought that they were voting for/against proportional representation were just plain wrong. That's just plain not what the referendum was for.
Are you saying that these people were not misinformed? That somehow, even though the referendum was not about PR, and they thought it was about PR, they were still right? Is this some kind of "prizes for all, everyone's correct in their own way" situation?
When faced with the exact same evidence, a majority of people will react the same way.
What's more likely is that the sum of the evidence isn't actually the same.
People will generally vote based on what they know (the evidence that's been presented to them). What they know isn't much for most of the population - it's whatever TV channel they watch, whatever newspaper or website they read.
IOW, anyone who disagrees with GP is, in fact, likely to be misinformed - at least from the point of view of GP.