The way I read his comment was a difference between perceived value and actual value. Market share is equivalent to perceived value, not actual value. So the comment was remarking that the drop in share price could be the result of inflated expectations becoming more realistic rather than a loss of actual value of the company.
The biggest difference between perceived and actual value that I'm aware of is the tulip mania that early 1600s. In hindsight, it's pretty obvious that flowers didn't become less valuable in the short time period between the height and the collapse. Any utility or purpose they had, other than resale, was retained in its entirety. But the price difference was massive. There are many who believe we're in our own era of unicorn mania where it will become apparent, again in hindsight, that they were never as valuable as people made them out to be.