[usrusr]

"The tragedy of publicly traded companies" sounds like a very useful term! But I don't think that you need to look any deeper than the basic market mechanism of shareholders with realistic expectations happily selling to future shareholders with higher expectations (e.g. unrealistic expectations). If the latter exist, they will offer more than the former think the shares are worth, deal. It's a market mechanism as basic as gravity, "race to the least pessimistic".

The only thing that sometimes prevents it is when holders are emotionally attached (old family stock or brand fandom) or when holders have a strategic need to prevent certain control scenarios (often nationally flavored).