People became the fastest billionaires in the shortest amount of time

Eric Lefkofsky – 3 years

Eric Lefkofsky had founded several successful firms before he co-launched Groupon in 2008, but it was the daily deals site that made him his first $1 billion. The business guru cleaned up when Groupon went public in 2011, just two and a half years after its creation, and entered the billionaire club the same year.