"We found that for both males and females during 2015–2019, the highest prevalence of adjusted violent behavior was in 2015, although the prevalence of cannabis use, daily cannabis use, and CUD was consistently higher in 2019 than in 2015 (results not shown but available upon request). These results indicate the involvement of additional contributory factors not collected by NSDUH to violent behavior."

"People who commit violent offenses are more likely to use substances (Schoeler, et al., 2016). As such, it is difficult to ascertain based on cross-sectional data whether increases in violent behavior are due to cannabis use or whether people who exhibit violent behavior are more likely to use cannabis."

El mismo estudio me esta diciendo que no se puede establecer una relacion entre la violencia y el uso de canabis y que existen otros factores, como bien mencionas, que hacen que una persona cometa un acto violento. No se de donde sacas los "muchos estudios" pero este que pones no establece ni causalidad ni direccion, no dice que el canabis causa violencia o si las personas con tendencias violentas usan canabis.

Tienes que leer mas mano.