It's basically the life cycle of the internet. A thing is created for the people, it's beautiful and loved, it is not profitable at all, they use their newfound user base to generate money, they abuse their user base to generate even more money, a new "for the people" alternative springs up, mass migration.

Skype, digg, and MySpace sort of followed that trend. Now reddit is completing the cycle. YouTube should be next, but it's significantly more expensive to make an alternative. But I remember when making money from YouTube was a south park punchline. Those were better days.