What wasn’t fair about it, well publisised and everyone eligible given a chance to have their say by voting.
More people voted out than in, seems pretty straight forward to me.
From both sides:
Disinformation
Lies
Witholding important facts
Ignoring possible consequences
Calling a referendum under the pretence that the government wanted to give the people a choice when in fact it was a last ditch attempt for Cameron to hold his party together.
Russia and US meddling.
Having a vote on a subject the vast majority of us are not qualified to assess fairly
Changing the law to make the result legally binding.
Lies and more damned lies. It was not a fair nor honest vote.