@nprofile1q... boring answer: UHC didn't cease operations when Brian Thompson was killed. the systems of power capital has built are generally (not always, but generally) too durable for random political violence to interfere with their operation, and they've manufactured consent thoroughly enough that even several such killings wouldn't land in the popular mind as a mandate.
also the average human most oppressed by these systems is kind, peaceful, and has too much to lose to sacrifice their lives.