In October, after Microsoft acquired 1.6 percent of Facebook for a whopping $240 million, Gates began receiving more than 8000 friend requests per day, causing him to quit using the site, according to the UK newspaper The Sun.

Also factoring into Gates' decision was the emergence of bizarre Facebook groups which bear his name, according to The Sun. Maybe Gates was spooked by the existence of groups such as "Kick Microsoft out of Facebook!" and "F--- You Bill Gates."

Or, perhaps Gates took issue with "Bill Gates Reads Your Facebook," a group that appeared shortly after Microsoft announced its Facebook investment, which warns members to "make sure anything you post online isn't something you wouldn't want Microsoft to take and resell."

It's even possible that Gates was still skittish about Facebook's controversial "Beacon" feature, which angered users late last year by sharing their personal user data and purchasing history with advertisers and other 'friends' on the network, prompting an apology from Facebook Founder Mark Zuckerberg.

Whatever the reason, most industry analysts would agree that Gates would be best served by focusing his attentions on figuring out what he's going to do after his last day at Microsoft, just in case he's got any free time left over after his upcoming transition to the field of philanthropy.