Except Rittenhouse did nothing to incite Rossenbaum to attack him. Rossenbaum himself was in fact trying to incite violence earlier that night by helping to push a burning dumpster into a gas station and taunting several other people with firearms to shoot him. We have had an eye witness since this happened that saw what happened before the videos of Rittenhouse being chased begin and he (A reporter) was talking with Rittenhouse before they saw Rossenbaum and some other people walking toward them. Rittenhouse then ran and Rosenbaum started chasing him.
In every instance, Rittenhouse was taking actions to get away and NOT fire his weapon. Every time he fired his weapon it was when he unable to retreat and the person was attempting to grab or attack him. In the case of Rosenbaum, he was trying to take Rittenhouse's gun and it was also after someone else fired shots in the air. The second time, he was attacked by the guy with the skateboard, who also tried to take his gun. The third time was after the guy with the pistol motioned as if he was going to back off, only to then lunge in with his pistol (Which he was also not legally supposed to have) in an attempt to shoot Rittenhouse. Right after that shot, you can see in the camera footage that some guy about to run up to Rittenhouse stops when he points his weapon at him, raises his hands, and backs away without further incident. His first actions after this was to walk up to the police and attempt to surrender himself to them.