Mr. Musk is fundamentally a creature of Silicon Valley, a scene that initiated an entire revolution in power dressing. The young masters of that universe dressed down to show that they were members of a new elite — one that refused to dress like the grown-ups they were about to topple. It was the defeat of the suit by the T-shirt.

After a slight rebound earlier this week, Tesla's TSLA stock is back to falling, keeping with its recent performance. Even U.S. President Donald Trump's purchase of one hasn’t done much to spark real momentum for the electric vehicle (EV) leader.