Thanks !
Notice that the liar Comey is pushing hard a contrary version, that he was fired because his Russian investigation was a threat to Trump or members of Trump's team.
I suppose it's true that the (manufactured) Russian investigation was a threat, but I see it as a McGuffin. The FBI was going to manufacture an issue to bring Trump down. That is the story. The fact that the issue was "Russia" is secondary, and any other manufactured issue could serve the same purpose of advancing the plot line.