I'm not sure why you're talking about unicorns, or why you think the true scotsman theory is applicable in this situation. In your example then I've never thought the conservative party were "True Brexiteers". I don't think many Brexiteers do, this is why UKIP did very well in the Euros and now the Brexit party. The existance of those parties shows that people don't trust the Tories to deliver Brexit. So because you are replying to me I'll reply from my own experience. Though I voted for Brexit I never trusted the Tories to deliver it. I misguidedly thought that leaving the EU would make the British government actually have to take some responsibility for themselves now it wouldn't have someone else to blame. But since that vote I have realised that the government is acting so incompetent and we're probably better under some kind of control of the EU. As new information comes in and situations change then everyone is entitled to reassess and not be pig-headedly staying to their original opinion.