It does not have to be what you descrbe, but it cannot be denied at all that there is evil in the world and it is NOT from God.
Sure, but just because it isn’t from God doesn’t mean it comes from Satan. We have free will, and we freely choose evil often enough. So, Occam’s razor dictates that if there is no supernatural phenomenon that would indicate demons, it’s most likely just good old-fashioned human evil that we are dealing with.