Sometimes a person wants to own shares in a company but plans to wait until "just before" the price per share rises before buying. I have bad news for such a person: those who have what is sometimes called "dead money" invested in such a company are unlikely to roll over, play dead, and sell to newcomers if prospects brighten unexpectedly.
A corollary is the mistake of selling shares that one thinks are undervalued in the hope of buying them back when they are even more undervalued. (I have made this mistake in CMLS upon becoming Mr. Scared.) It's a good way to lose out on big long-term winners when the share price "refuses to cooperate" by falling.