In retrospect, Tesla was undervalued, but this wasn't a guarantee. Elon is a loose cannon with a history of overpromising to the extent of borderline lying. This got him in trouble with the SEC (funding secured), and he lost his board chair position and could have been ousted as CEO. In hindsight, the SEC obviously wouldn't screw over the fastest growing American company for a dumb meme tweet, but this isn't something people knew at the time.