The vote and triggering of Article 50 were after the event. The result, after the event, is not the issue. The referendum itself would never had been on the table but for Cameron's paranoia over Farage and UKIP. He just happened to be the Tory leader that finally bowed to 50+ years of infighting...
Er, the Tories have been tearing themselves apart over Europe ever since we joined the EEC. Brexit is directly linked to the Tory paranoia with UKIP and Farage.