Violence is not categorically bad. Violence is a tactic that is sometimes necessary and sometimes good. For example if you are being attacked, it is completely justifiable to defend yourself, violently if necessary.
BLM is fighting to end police violence against the Black community. Antifa is fighting to stop white supremacists from gaining power in the streets and in government.
The people who attacked the Capitol were fighting to end democracy and keep an unelected would-be dictator in power.
