Why do centrist act like the left is just as bad as the right?

Jumping on the conservative hate train because yeah, they’re awful and should be ashamed of themselves. But I have a question for those who are still somehow on the fence of our countries historic ruination. I often hear the phrase “both sides are bad” when someone doesn’t have a clear political side. But with how cruel and inhumane trump’s right wing minions are running our country, I don’t know how anyone can pretend the left is equally as evil. Biden was at worst, incompetent, and democrats shot themselves in the foot but allowing that senile bastard run again and then not even having another primary after he finally realized he was too old. Now that we see what happens when republicans have the majority of the power of our government, it’s blatantly clear how the right is owned by the rich to exploit the masses. Moving the tax burden from themselves to us with the reckless addition of tariffs while they get tax cuts and essential government programs are shut down. Can anyone tell me how the left is just as bad?