Trump wanted a team who could present all sides of an issue, Bolton believed Trump hired him because he agreed with Bolton’s vision, which was not the case. Bolton certainly could make his case, but Trump was listening to others as well, and ultimately, Trump didn’t agree with him.
I assume Bolton gave too many details of his interactions with Trump to his CNN buddies and the recent Taliban thing was last straw.
If Bolton really believed that, then he’s a moron. In the 2016 primaries Trump beat the sh!t out of Yeb Bush from one end of the country to the other by hammering him over the nonsense that people like John Bolton brought to the GWB administration.