> Stumbleupon had a declining user base because more and more spam flooded the site. Moderation couldn’t just keep up to it. As a result, advertisements were increased to keep up the profits from the remaining users. As you might imagine, this pushed those remaining users off the site even more. At some point, the management decided to put effort into a new platform: Mix.com. The CEO also spent a lot of his time building Uber (yes, the taxi company).