What drives them? Most likely paid agitators. Monkey see..monkey do. Unfortunately, kids like Kyle Rittenhouse who killed two people and wounded another get caught up in it. From all reports and interviews he gave prior to the incident, he was a well-meaning kid, a police cadet, looking to protect not destroy. (This is not right leaning propaganda but my own evaluation from what I observed). I'd have to go with self-defense on what is known at this point. Here's an article about it.
https://news.yahoo.com/does-kyle-rittenhouse-self-defense-151458174.html?ocid=uxbndlbing.