I have no desire to re-hash this particular argument, but the margin, 48/52 was very small. Very close to 50/50. And the turnout wasn't perfect. I've heard that only something like 30% of the eligible voters voted to leave.
There was no "will of the people". The people were undecided.
And then there's the fact that Britons settled in Europe didn't have a vote.
Whatever you can say about voting rights for overseas citizens in general elections, this vote was explicitly removing rights that they are currently exercising as part of EU membership — arguably they are the most affected by the outcome, yet were disenfranchised.