Setting that aside, I don't know that his feelings toward other random people does much. If a person threatens to stab one individual two weeks before stabbing someone entirely different, does that really establish a pattern? Likewise with them not being able to show that he had fleeting contact with the Proud Boys.
I think it is evidence that he was in fact 'looking for trouble'.
Even a racist hothead is allowed to defend themselves, if they are not the aggressor.
So let's assume for the moment that Rittenhouse might be willing to lie to avoid going to jail - just as he was willing to lie about being an EMT. He is on recording admitting he pointed his gun at someone (he claimed on the stand that he was lying when he admitted it). He is on the surveillance video following Rosenbaum and then Rosenbaum appears to try and hide in the cars then runs after Rittenhouse and is shot.
1) If Rittenhouse points the gun at Rosenbaum - he commits assault with a deadly weapon - then Rosenbaum would have a reasonable fear for his life, and being unarmed might reasonably try to disarm the person who threatened him. Then trying to disarm Rittenhouse is self-defense and Rittenhouse is the aggressor.
2) Then all of the deaths that follow are not self-defense. Instead we have someone who was threatened with a gun trying to disarm the person with the gun, who is shot, and then the shooter shoots additional people who try to disarm him.
All that matters was whether he was being aggressive on that night, not whether he was generally an aggressive person.
We have an audio recording that he admits is him, where he affirms that he pointed his gun at someone, it is only now that he is being prosecuted that he claims he lied about engaging in that crime. People generally don't lie when the admit to a crime, it is when they are being investigated for crimes they are likely to lie.
Generally speaking deaths that are a direct action of a prior crime are murders and not self defense even if it would normally be self defense (ie you rob a bank, the bank guard pulls his gun and you shoot him - it is murder, even though if the guard had done so without your bank robbery it would be self defense). (But not if they are indirectly related - so illegal possession of a firearm for instance wouldn't negate self defense).