Nvidia may be the most impressive business in the market. That does not automatically make every price a bargain. Here is what investors are really betting on at roughly $224 per share. There are two conversations about Nvidia, and they rarely occur in the same room. In the first conversation, Nvidia is building the computational infrastructure for the most important technological transition in decades. Its chips power the artificial-intelligence systems that every major technology company is racing to develop. Revenue is growing at a rate normally associated with a small software company that just discovered customers, not a corporation already worth more than $5 trillion. Gross margins resemble those of a luxury tollbooth positioned directly across the only bridge to the future. In the second conversation, Nvidia is priced as though the future has already arrived, signed a long-term lease, and agreed to annual rent increases. The company may continue producing astonishing numbers and...