Edit: And it certainly doesn't translate into 52% of people wanting him to win in 2020. If he negotiates a poor deal with the EU and/or 'forgets' about a few central 'Leave' arguments, he'll be in all sorts of trouble.
You have to understand how those people operate. They don't give two bits about reason and making sense. All they care about is to stay in power. They optimise for that and that alone. And 52% is power, beyond BoJo's (or Gove's or Farage's) wildest dreams.
If Brexit was a big mistake, thinking that Boris will get cold feet now that he has a clear line of sight to his goal (to be PM, duh) is an even bigger one.
That's not how it works - that 52% is not some uniform body with similar goals and vision beyond Brexit. This is the same challenge facing many popular revolutions - there is little uniting them beyond ousting Gaddafi, or "the 1%" (add Brexit to this list). Once they have "won", suddenly they realize they can't cater to everyone's wants and the whole thing splinters into factions.
But, that is somehow making him do a sad face?