'The first billion is the hardest': Here's how long it took 21 entrepreneurs to go from millionaires to billionaires

One million and 1 billion are two different numbers, and as business mogul T. Boone Pickens likes to say, "The first billion is the hardest." Yet Facebook founder Mark Zuckerberg was able to go from millionaire to billionaire in just one year at 23 — which made him the youngest self-made billionaire in history at the time. To see how long it took some of the other richest entrepreneurs to grow their fortunes from six zeroes to nine, check out this infographic from UK-based direct-funding company and web platform Fleximize:

billionaires

(fleximize.com)

Click here for the interactive version of the graphic.

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