He's not oblivious to it, he just doesn't care. Why should he? His ego is the only thing that matters, other people are a means to an end. He has the same low cunning as trump, I think he's quite good at reading people, and manipulating them, but others are just tools to him. He is remarkably similar to Trump in fact, and as Sarah Kendzior said about Trump:
"If Trump senses he may have to make a personal sacrifice, he will sacrifice the world instead."
https://www.fastcompany.com/40558314/donald-trump-will-do-an...
The same holds true for Johnson. He will happily sacrifice the UK for the sake of his political career, so that he can be prime minister.