The question isn't whether there's a bull case for tesla, there obviously is. The question is the bear case which the GP laid out pretty clearly.
Tesla might grow to eclipse the existing auto industry! Certainly the story of "incumbent industries fail to adapt to changing conditions" is a common one but "industry supports several equally sized competitors" is as well.
I just said it above, extrapolating from past exponential performance works until it doesn't and reality implies that it will stop working at some point.
