#6 Viddy's Brett O'Brien walks from a reported $100 million buyout

Brett O'Brien's startup Viddy was a sensation; it offered simple way to share well-produced, bite-size videos with the world. Photo-sharing app Instagram had just been acquired by Facebook for $1 billion, and Viddy—often called the "Instagram for video"—had about 30 million monthly users.

Twitter reportedly came looking to buy the company for somewhere in the $100 million range, but Viddy walked out of the deal.  However O'Brien denies those reports, saying the Twitter talks didn't progress into an actual offer.

It was too bad that O'Brien didn't get Twitter to make an offer. Viddy's popularity has since taken a nosedive and O'Brien has to get down as CEO of Viddy.

#5 HP execs said no to Woz five times

Back in the 1970's Steve Wozniak worked for Hewlett-Packard designing engineering calculators. In his spare time, he created a PC that would later become the Apple 1 computer.

Five times, Wozniak begged the executives at HP, lead by then-CEO John Young, to manufacture his PC. They said no. So he left HP to start a company called Apple with his friend Steve Jobs.

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