The investors are tasked with making money. The investors are going to have made a lot of money after the IPO. It doesn't matter much to them whether the Groupo

The investors are tasked with making money. The investors are going to have made a lot of money after the IPO. It doesn't matter much to them whether the Groupon CEO took their money and rolled it up and lit it to make a really awesome bonfire, if the investors put in $1 billion and get back $10 billion they're happy. That's why they allowed it, and it's also why they turned down $6b. They're all acting in accordance with their financial incentives.