Because without being a charlatan and a liar he would only last a few days or weeks.
Basically, as many on here have suggested, he's a crook with a posh accent.
He gets holidays bought for him by the most unpleasant of characters.
Another fraudster intent of self enrichment at any price.
Johnson seems to attract them like flies round the proverbial. https://www.bbc.co.uk/news/uk-politics-51482220
Johnson is also on record of admitting being approached by convicted (and imprisoned) fraudster Darius Guppy, who was (is?) a personal friend, to supply journalists addresses so those journalists could be beaten up.https://en.m.wikipedia.org/wiki/Darius_Guppy
Johnson's and such friend's only motivation is personal wealth, in my view, and that very likely overrides even Johnson's ego driven lust after power.
He is just a series of soundbites, provided by the soundbite man Cummings.
There is nothing for honest and humble folk in such a PM.
He will bleed them dry.
The sad fact is that through the con that was Brexit many such folk were successfully fooled.
The only small consolation lies in the thought that "give them enough rope etc".
As confidence and the corrupt network builds, one day the mask will irrevocably slip.