This is kind of a silly argument. Let's say, to take an extreme, you _know_ a stock will fall dramatically at some point in the next five years, but you don't know _when_. You know that, until it falls, it'll be pretty volatile, and sometimes jump up. So, when do you short it? You probably do not short it on day one; that's going to be horrendously expensive.

Really, betting against any tremendously hyped stock is a very dangerous exercise. Just ask those who shorted GameStop (which is _clearly_ dramatically overvalued, but is back to happily jumping up 10% in a day just because).