By Valerie Vande Panne CAMBRIDGE, Mass. (Reuters) - Facebook founder Mark Zuckerberg returned on Thursday to Harvard University, the school he dropped out of to start the pioneering social network, to urge its graduating class to help create a new social safety net to allow creative risk-taking. The 33-year-old tech founder of the world's largest social networking company said he would never have been able to risk leaving the elite Ivy League school if he had not known that his family would have been able to support him if he failed. "There is something wrong with our system when I can leave here and make billions of dollars in ten years when millions of students can't afford to pay off their loans, let alone start a business," Zuckerberg told the crowd on a cold, drizzly day when graduates' dark academic robes stood in contrast to the brightly colored plastic rain ponchos scattered through the audience. "When you don't have the freedom to take your idea and turn it into a historic enterprise we all lose," said Zuckerberg, who was also named an honorary doctor of laws. He offered no specific solutions to the problems he highlighted, but urged graduates to contemplate them. Since its launch in 2004, Facebook has inspired a host of competitors, including Twitter Inc and Snapchat . Today some 1.9 billion people use Facebook each month. Its broad reach has made the company a lightning rod for controversy, most recently for the ways that producers of fake news stories used it to influence public opinion during the 2016 U.S. presidential election, and for a pair of incidents last month in which users posted videos of two murders, one of them live. The Menlo Park, California-based company has vowed to tackle both problems and this month said it would hire 3,000 new workers to speed up the removal of videos depicting murder, suicide and other violent acts. Earlier in the day the website of the school's student newspaper, The Crimson, was briefly filled with satirical headlines about Zuckerberg. The newspaper on Twitter apologized to its readers for the incident. Zuckerberg's speech was not the first time a successful dropout returned to the campus in Cambridge, Massachusetts, to address graduates. Microsoft Corp co-founder Bill Gates spoke to graduates in 2007, shortly after saying that he would step away from his day-to-day role with the world's largest software company to focus his time on philanthropy. (Writing by Scott Malone; Editing by Steve Orlofsky and Chris Reese)