MASSIVELY PASSIVE INCOME: MOOCs stand for "massively online open courses." On Udemy, there's apparently massive money to be made as well. The San Francisco, CA-based online learning marketplace, which boasts more than 20,000 courses and 5 million students, says its top 10 instructors have earned a total of $17 million. One Udemy instructor even teaches a course on how to make money on Udemy. The company has so far raised $48 million in venture capital.