History only remembers the winners.

But, unlike as in war, in business, entrepreneurs choose to retreat, not having enough faith in the battle or the battalions to fight till the end. 

The result can go down in history as a brutal mistake made by an entrepreneur who could have been a billionaire today, had he stuck around to see his company through to becoming one of the most successful ones.

1. Joe Green, Facebook

In the fall of 2003, Joe Green helped Mark Zuckerberg create Facemash, a website that allowed users to compare and rate the faces of Harvard undergraduates for attractiveness. Both Green and Zuckerberg were threatened with expulsion by Harvard’s administrative board.

This led to Green's father advising him not to work with Zuckerberg on any future projects.

When Zuckerberg asked Green to come into the Facebook project, Green had to decline, because his father didn't want him to do it, thus he had to give up Zuckerberg's offer of shares in Facebook. These shares would have been worth billions of dollars at the time of Facebook's IPO.

2. James Monaghan, Domino's

With a $75 down payment and a loan of $900, brothers Tom and James Monaghan bought their first pizza store, called DomiNick's, in Ypsilanti, Michigan, in 1960.

About eight months after taking over an ailing pizza restaurant, Jim Monaghan wanted out. He owned 50 percent of the business (which today rakes in more than $10 billion annually), and cashed out by taking the beatup ’59 Volkswagen Beetle the brothers had bought as a delivery car.

Tom Monaghan, on the other hand, sold his controlling stake in Domino’s Pizza in 1998 to Bain Capital, an investment firm based in Boston, for an estimated $1 billion.

3. Ronald Wayne, Apple

Ronald Wayne worked with Steve Jobs at Atari before he, Jobs, and Steve Wozniak founded Apple Computer on April 1, 1976. Serving as the venture’s “adult supervision,” Wayne drew the first Apple logo, wrote the three men’s original partnership agreement, and wrote the Apple I manual.

Wayne received a 10 percent stake in the company. He was 40 years old at the time, while Jobs and Wozniak were only 21 and 25, respectively. Legally, all members of a partnership are personally responsible for any debts incurred by any partner; unlike Jobs and Wozniak, who were young and without many liabilities, Wayne had personal assets that potential creditors could seize.

And so, just 12 days after Apple was formed, Wayne sold his stake for $800, receiving an additional $1,500 later that year in exchange for forfeiting any claims against the company. His stake could have been worth more than $75 billion today!

4. Toby Rowland, King.com

Toby Rowland co-founded King with Melvyn Morris and Riccardo Zacconi and was co-chief executive until 2008, but he sold his shares in 2011, just months before the company launched its first hit Facebook game.

He sold more than 40 million shares back to the company at a mere $3 million.

Had Rowland kept his shares, he would have been King.com's largest individual shareholder. King.com's IPO valued the company at $7.6 billion, making Rowland's former stake worth $966 million.

5. John Sylvan, Keurig Green Mountain

The company was founded in Massachusetts in 1992. It launched its first brewers and K-Cup pods in 1998, targeting the office market. As the single-cup brewing system gained popularity, brewers for home use were added in 2004.

Last year, K-Cups accounted for most of Keurig Green Mountain's $4.7 billion in revenue.

However, in its early days, Keurig needed sizable venture capital; and after pitching to numerous potential investors, it finally obtained $50,000 from Minneapolis-based investor Food Fund in 1994, and later the Cambridge-based fund MDT Advisers contributed $1 million.

John Sylvan, one of the founders of the company and the inventor of the K-Cup, did not work well with the new investors, and in 1997 he was forced out, selling his stake in the company for $50,000.

Peter Dragone, the other founder, however, left a few months later but decided to retain his stake.