In practice that doesn't happen. In these late-stage rounds, there is not usually a single investor willing to pay way more than other investors. And even if

In practice that doesn't happen. In these late-stage rounds, there is not usually a single investor willing to pay way more than other investors. And even if there were, the company would think twice before selling at that price, because it would just set them up for their next round or IPO to be a down round, which would not be good.