There are a myriad of reasons why Donald J Trump ran for president.
First of all, ever since the early 80's he's been on record as at least entertaining the idea. He has also been remarkably consistent in his aims.
In one of the first interviews that discussed this he mentioned how the 'United States gets ripped off' in trade. His populist sentiments were early. Neither liberal nor conservative, he forged a pragmatic policy of strong defense, resisting foreign entanglements, and wanting to keep commerce within the country as much as possible.
These core values never really changed.
Media pundits love to point out that he 'used to be a Democrat'. There was no future to being a Republican working within Manhattan business and social circles, so it was, like other determinations a sane and reasoned decision.
The left wing planks of the party were not an issue for him. He wasn't a politician.
But over time this arrangement started to fray. While he got along fine with Bill Clinton, another pragmatist (to an extent) he disagreed strongly with the Bush administration's foreign policy.
Yes, it's true he supported the invasion of Iraq very early. But he changed horses soon as well. Unhappy with the prosecution of the conflict he sounded off on how unwise it was. This was not uncommon among others on the right, either.
The war was prosecuted failry well. It was the aftermath that was either severely bungled, or a concrete decision was made to create these now continuing 'vacuums' that allow a known enemy to arise- Al Qaeda, ISIS, Daesh- that serves a purpose.
It allows the establishment -this would be your 'deep state'- to knock over, one by one, sovereign states in the region. These vacuums would be filled by these groups, who would export their violence into the next country.
Senator John McCain has been right in the middle of all this. His picture with 'moderates' in Syria now a well known joke that isn't very funny. Here's a decent recap:
So, one could say that there are a multitude of reasons why Trump decided to run. But one was personal. That eponymous event?
The White House Correspondent's Dinner in 2011.
The last president used that forum to openly ridicule the New York billionaire, who despite the contrary can take a ribbing. He has been roasted more than once. But the Leader of the Free World took it to him, and took it good.
Roger Stone, a long time Trump adviser, put it succinctly:
'That was the moment Donald Trump decided to run'.
It was also the genesis of the extremely deep dislike the two have for each other, contrary to the 'nice-nice' on the surface. There is absolutley no love lost there...
The campaign begins