I agree that this was part of it - I referred to this twice in my original post.

Once the structural body concept failed (has it ever been adequately explained why they failed?) it would have made sense to either drop the Cybertruck altogether, or pivot to a more traditional design. But ego prevailed, sadly.

IMO the big missed opportunity was to follow the model 3 with a 'model 2' - a smaller, cheaper car - probably in the VW Golf / BMW 1-series class.