(This is a philosophical question. Just exploring ideas)
Increasing number of people have nothing to lose. Rioting is pointless and dumb and can land you in jail. People publicly writing "bad stuff" on social media are risking jail-time or at least having their lives destroyed.
Why is nobody killing the rapists and murderers? Why is there no secret organization cleaning up the streets? Why are politicians and "public servants" allowed to feel safe?
I think this is a historical anomaly.
Even here we have posters that constantly bitch about people doing nothing but what wpuld happen if someone said "i did X." Those posters would report them.
If you want vigilante justice, start prepping, start planning, and accept losing everything as a potential cost of your actions.
The other problem is comforts. Even with our nations burning, we have food, we have shelter, we have sexual release. We lack meaning and purpose. We lack a system that supports us. Even if you dont have the stomach for vigilante justice, do you have resources to help, hide, feed, or equip the warriors?