It's not clear to me. I think you are taking it as self-evident that Leave is a bad idea. In the mainstream narrative, the EU is associated with everything nice and international and the only reason to be against it is if you're a crazy old-fashioned nationalist.
There's a classical liberal case for Brexit, though, which Gove articulated reasonably well. I think Johnson kinda believes the same things, though without Gove's conviction (I voted Leave but I don't like Johnson, I think he's an opportunist). Like all conspiracy theories yours assumes that the conspirators concoct these elaborate schemes which have multiple failure modes. Leave had roughly 1/3 odds of winning all through the campaign, so it's not that much of a surprise. Nor is it clear that a Remain vote would have helped Johnson's career, given that almost the entire establishment backed Remain.
> It's startling watching the "moderate" Leave wing falling over themselves to dial back all of their promises during the campaign.... turns out there isn't more money for the NHS...
The media is really playing up this angle. Vote Leave isn't the government and the referendum wasn't a general election where the campaigners campaign on a particular manifesto. There is now more money in the UK budget, where it gets spent is up to the next PM.