You're right that a higher market cap is one definition of success.
Keeping it high is another.
Electrification of human transport is another.
I suspect he wants it all, and having a higher market cap right now is a way to get the other two - TSLA raised a massive amount of capital off of their high valuation.
If Tesla cars were such POS, they wouldnt be growing 50% Q/o/Q. They have the most popular selling cars in multiple countries (Model Y).
The news picks up on the .0001% of problems and those customers are always the loudest (understandably). For ever cracked front casking, there are tens of thousands of solid castings. Austin alone makes 5K Ys per week.