Malcolm X, JFK, MLK, and RFK's assassinations were horrible, but I think they ultimately galvanized a lot of people towards action because of their violent natures. The 70s saw a lot of political activism even as the Baby Boomers were starting to get old and become parents themselves. I think John Lennon's murder is the straw that broke the camel's back though, and utterly decimated the idealism that Baby Boomers of the 60s and 70s had. I think JFK's assassination kickstarted the fight by the Boomers, but Lennon's death was the end.