"Think about a company with a market cap of $500 billion.

To justify paying this price, you would have to earn $50 billion every year until perpetuity, assuming a 10% discount rate.

And if the business doesn't begin this payout for a year, the figure rises to $55 billion annually, and if you wait three years, $66.5 billion.

Think about how many businesses today earn $50 billion, or $40 billion, or $30 billion.

It would require a rather extraordinary change in profitability to justify that price."

Warren Buffett