I'm not really talking about fear. Ideology is a powerful drug, you have to try and give them crack or lsd or something to temporarly get them off of ideology like the CIA tried to do. Also why tharapists prescribe increasingly stronger psychoactive drugs, it's to ideologically subdue the patient. Peer pressure has little to do with it. One can be socially conditioned into conpliance yet they will still voice thier discontent, it's what you see with online dissidents today, they fall into peer pressure of compliance but they hold onto the childhood ideology they formed when they began pubescence.
So there is a way and it's usually constant supply of drugs or death. (Maybe I'm projecting here in that I'm living in country that is a insane asylum and that things arn't exactly this way with other peoples, my country has ever shifting and more nonsensical narratives every successive generation, they have to find a enemy and when they defeat a enemy and made whatever is left into a friend they have to manufacture another enemy within the friend for some inexplicable reason. Every generation has to deal with the previous generations lies and cope with the newfound lies they tell themselves)
In terms of ideology being like a "powerful drug", it most likely relates to the need for adolescents to feel like they are a part of a group. This would explain quite well why there is a need to become involved in social movements because the adolescent views participating in societal causes as something adults do, and thus this leads to ideological imprinting on a developing mind.
Relating to pharmaceutical and recreational drugs, it's really more of a method to tamper with someone's deeply held memories so the person in-taking the substances feels different about their past experiences, and seeing those memories in a new light.
The internet is really an elaborate venting machine in a sense that you describe on how even after someone is forced into compliance they still voice their "unapproved" opinion's onto the web.
Giving the public a common enemy to fight against is a classic controlling tactic used on the masses to rile them up for some "greater cause" by authoritarian elites.
For the last part its most likely that the current generation identified the problems the previous generations solutions had to a particular problem, and now they're making mistakes trying to solve those problems just like their forefathers did.
