The fundamental problem is a misunderstanding of where the political center is. Elon exhibited this misunderstanding brilliantly in a political cartoon he posted on Twitter last year.
The same misunderstanding has been expressed in this thread saying views here about Elon & Twitter that match the views of Dave Lee and Lex Fridman are from a group that is extremely left-leaning.
This one misunderstanding combined with an intransigent disregard of the mountains of evidence to the contrary explains everything else. For example, if Musk were correct that his political views, exemplified by such things as linking himself with Kanye and Trump; pushing an alt-right conspiracy theory about the husband of a prominent Democrat; or acting like a juvenile schoolyard bully (see how he treated Kara Swisher), were mainstream then it makes sense that the lack of advertisers must be due to pressure from radicals on the left and not his own off-putting behavior.
One of the things I most admire about Elon Musk is his ability and willingness to learn from his mistakes. While this is true in technical fields it has, unfortunately, not carried over to his idea of what is politically mainstream. He sees himself as standing up for the political center and waging the good fight against wokeness, leftist radicals, or whatever nom de jour he uses to dehumanize those he disagrees with.
This illustrates the dangers of having a reality based on emotionalism, name calling, bullying, and conspiracy theories. Once you fall down the rabbit hole, it's very hard to climb back out because all evidence to the contrary can be explained away by a vast other-wing conspiracy.