4. Failure to buy Groupon, 2010
On November 4, Groupon, the daily deal service went public, and raised $700 million, making it the second largest initial public offering by a U.S. Internet company since Google raised $1.7 billion in 2004. Groupon is now valued at $13 billion. Last year, Google failed to buy Groupon for $6 billion. Many said it was crazy for wanting to do and the search giant backed off after talks stalled. Who's crazy now?