Maybe not even that. The people who bought at the top might not be the ones who sold. The ones who sold might be long-term investors who are still in the black because of the stock's huge growth in the last 5 years. Someone who bought the stock exactly a year ago is only down about 1.5%. Someone who bought 5 years ago has almost doubled their money.

All that has really happened is that the collective opinion of all Alphabet shareholders is that the company was overvalued by about 15% compared to what they thought it was a couple of days ago.