Boris Johnoson is an educated man and I don't doubt his intelligence. What I was referring to was his decision to back Brexit and go against David Cameron during the 2016 referendum, which to my mind is what put him in line for the premiership. The way I see it -it's entierly an interpretation from what I've read in the news- Johnson had wanted to be Prime Minister in the place of the Prime Minister ever since he joined the Tory party. When David Cameron proclaimed a referendum, Boris Johnson spent some time on the fence, trying to decide whether he should back Brexit, or back Cameron. His criterion must have obviously been the chances of becoming Prime Minister in the place of the Prime Minister, depending on the choice. Eventually he decided to go against David Cameron and back Brexit, which from my recollection was seen as a big bail on Cameron. I believe, neither Johnson nor anyone else could predict the outcome of the referendum at the time, so Johnson basically gambled. He would very likely be sidelined for a long time if he chose wrong. He happened to choose right, fell on the side of the penalty kick and positioned himself in the line to the throne.
But none of this happened thanks to his careful planning. Johnson was lucky to be associated with the Euroskeptic Tory right as an attack journalist writing defamatory pieces for EU institutions, before he joined the party. Then he struck gold when David Cameron put his head in the mouth of the wolf with the 2016 referendum.
He's an opportunist who got lucky.