In this chapter, I trace fanaticism’s roots in echo chambers, social epistemic structures where outside voices are intentionally depicted as vicious, untrustworthy, naive, or otherwise ethically and epistemically defective. We can find echo chambers in everything from diet groups and conspiracy theories to political parties and popular news pundits. Once an agent is ensnared within an echo chamber’s narrative, they begin interpreting all incoming information in the light of their background belief the outside world is striving to deceive them. Regarding the link between echo chambers and epistemic vices, I locate this connection in the act of entering an echo chamber. When an agent chooses an echo chamber’s simplistic and spectacular narrative rather than complex images of social reality, they exhibit the vices of epistemic laziness and gullibility. I close the article by claiming that we can prevent echo chambers by monitoring social networks and broadly followed news sources, but exiting an echo chamber remains an arduous and unlikely task.