As David Moyes' troubled time at Manchester United was coming to an end, a banner appeared at Anfield, home of arch rivals, Liverpool. It read "Agent Moyes: Mission Accomplished".

The idea was that the only way to destroy the dynasty built by Sir Alex Ferguson, United's legendary manager, was to do it from the inside.

I was reminded of the banner thinking about Donald Trump.

There are more than a few Republicans who believe his entire campaign is not geared at winning the White House but simply clearing a path for Hillary Clinton. A so-called "false flag" operation.

Remember, the Democratic nominee for president would be the least trusted candidate to run for the presidency if she wasn't topped by one other candidate. And that would be Donald Trump.

It's just one of the incredible conspiracies that have circled around the businessman's campaign.

It's no surprise. Conspiracy theories tend to arise as people try to make sense of unusual events. In fact in the book American Conspiracy Theories two respected academics found that "inducing anxiety of loss of control triggers respondents to seen nonexistent patterns and evoke conspiratorial explanations".

And the rise of Trump has been unusual and unexpected.

The suggestion that Trump is somehow a Democrat insider was given real credence in a tweet last December by none other than Jeb Bush. He wrote: "Maybe Donald negotiated a deal with his buddy @HillaryClinton. Continuing this path will put her in the White House."

OPINION: Welcome to the Trump show

So how could that possibly be true? Well first of all, Trump used to be a Democrat. He held and - in some cases - still holds views which are closer to Democratic orthodoxy than that of his own party.

He was a friend of the Clintons.

They attended his wedding in 2005. And he praised both Clintons, but especially Hillary, calling her "a terrific woman".

In the view of the man who first floated the idea, the self-described "conservative-paleo-libertarian" Justin Raimondo, Trump’s pronouncements, "the open racism, the demagogic appeals ... sound like something out of a Democratic political consultant's imagination, a caricature of conservatism as performed by a master actor".

Political outsider

Sceptics also point to the fact that any other political outsider would have been ignored by the media.

Instead, when Trump spoke it was covered wall to wall by the cable news networks and given extensive coverage in newspapers. Conservative talk radio lapped it up and promoted it.

And that, in part, is why Trump is where he is at. No other candidate could compete with his free media. He blew them off the air, and he blew them off message.

People such as Jeb Bush weren't able to push their own points or put forward their own policies because they were too busy responding to the latest Trump outburst.

He had toyed with a presidential run before and enjoyed the media and attention that came with it; this was the time he had to get in the race or be for ever branded a political tease.

Donald Trump won the nomination because, unlike any other Republican politician, he tapped into the fear and anxiety of America's working classes and gave it a voice.

He understood what they worried about most: a lack of economic advancement; the fear of immigration; and a concern that their world was changing too fast and they couldn’t pump the brakes.

Yet his most recent pronouncements - repeatedly calling Hillary Clinton "crooked", claiming the election will be rigged and stolen from the Republicans, are not the words of someone who wants a smooth transition of power or someone who wants his former buddy sitting behind the Resolute desk in the White House.

Trump is doing what he's doing because he wants to win the White House. Not for anyone else. For himself.