It's an establishment garden plot. Social problems seed the garden - angry seedlings sprout. Corporate media control weeds the garden - hate against the system is mocked by mainstream media, hate against scapegoats is amplified by right-wing media. The FBI then picks the ripened fruit in defense of the system - let some go to spread fear and uncertainty, catch others to send the message that the people are all weird bigoted terrorists, and the system is the only thing keeping them in check.