That works until there aren't any more marginal buyers. Just because some people out there are willing to sell the stock for $10 (which no rational person is when it's trading in the hundreds, by the way... the idea that there are marginal buyers who are somehow willing to vastly underprice their sales relative to the market value isn't a valid one) doesn't matter as long as large swaths of it are held by people who won't sell at that price.