Tesla’s premium valuation, long supported by high growth rates, disruptive technology, and Musk’s personal brand, is looking increasingly difficult to defend.

While it has taken investors on a bumpy drive, no one can deny that Tesla ( TSLA -1.75%) has worked out to be a wildly successful stock. In the past 10 years, shares have rocketed 1,700% higher (as of July 10). The company's revenue growth has slowed, to be sure, but Tesla is now consistently profitable, which is a positive development.