Why are you using the metric of annual revenues must equal market capitalization to determine whether a company is overvalued? And why use revenue instead of ea

Why are you using the metric of annual revenues must equal market capitalization to determine whether a company is overvalued? And why use revenue instead of earnings? Currently if NVDA can double their earnings next year they’d have a P/E ratio similar to MSFT. I think many investors believe they can reach this target hence the high valuation. Whether NVDA will continue to maintain this level of profit for the coming decade is another issue.