I think what's Elon is trying with the automation is very similar to difficulties that SpaceX had initially with reusable rockets. At first people doubted SpaceX can replace NASA, then that it was possible to do have rockets to return back, later when it started looking reasonable but SpaceX rockets were still crashing, company like Blue Origin were making fun of them by posting video that they can already land (omitting that just getting 100km up and back was far less challenging than what SpaceX was trying to do).
Eventually SpaceX succeeded and this resulted with much cheaper cost to send satellites to space.
To me it looks like Tesla is going through same thing, they try to automate all manufacturing instead of doing what everyone else is doing, this might make things bad at first, but once they succeed it will be very easy to scale the production and the only limitation will be the supply.
I believe in Tesla primarily because of Elon, he is kind of a guy who doesn't have word "failure" in his dictionary, if Tesla doesn't succeed then most likely what they were trying to accomplish was impossible.