Sarah Silverman is a purveyor of Social Justice Marxism propagandistic lies. This Neo-Marxist authoritarian hate cult is steeped in superstitions derived from authoritarian philosophers.
Her claim that “all serial killers are white guys” is not her own invention. It is a claim that originated in the indoctrination programs that were once, before they were taken over by authoritarian social engineers, institutions of higher education.
To disabuse yourself of this "gender studies" indoctrination, see these 101-level educational posts and start becoming familiar with some politically incorrect facts about serial killers: