It is not pretend, it's observation. I am not saying that every single person on the left is violent. Most aren't. The more radical the leftist becomes the more apt they are to be violent.
Just the domestic terrorist along should give you some indication. The Black Panthers, The New Black Panthers, The Weather Underground, the Students for a Democratic Society, Antifa, BLM and a whole bunch of other groups that I have heard of but forgot their names. All of them are or have been violent. You can even throw in the KKK and the Neo-Nazis because when they were at their worse they were Democrats. Many still are. Nazis are a radical left political ideology even if a lot of Neo-Nazis have joined the Republican party.
Aside from a small number of "Christians" who have attacked abortion clinics there are no violent right wing groups. That's because the further right you go the left you want to control other people. Anarchist just want to be left alone.
Those "Christians" were doing a bad thing for a good reason. I am not condoning their violence but on the other hand abortion clinics are baby killing machines. I cannot think of anything more evil than ripping a baby to pieces while it is alive just because it is an inconvenience. But I know you support infanticide so I won't say any more.
Then, like I told you before, ever since Columbine I have been closely watching who those mass shooter were. Although I have fallen behind on that in the last 5 or 6 years. Regardless, the vast majority of mass shooters in America are radical leftists. This is because leftists want to control people. Murder is a form of control.
The more radical left you are the less you value human life.