Notes given to President Trump to help him sell Teslas in front of the White House included prices and reminded him to use terms like ‘affordable.’

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.