Elon Musk wants people to invest in Tesla Inc. only if they trust it can make self-driving cars. Trouble is‚ the stock already trades at levels that assume the company has cracked that code‚ and then some. The electric vehicle maker’s shares are considerably more expensive than those of Nvidia Corp. and Microsoft Corp. — two mega-cap companies widely seen as AI pioneers. Yet‚ while earnings estimates for both these tech giants are rising‚ for Tesla they are plummeting — because EV demand is...