Yes, they exist to an extent. I can't vouch about why they do these things, because so personally do not agree with those type of practices. Most people that go so far as to sacrifice and rape usually end up in jail or prison. I honestly don't know why yup want to know this.
I just want to take a moment that Demonolatry is a valid thing and those that I know don't partake in "evil" activities. However, ritual sacrifice is something that many cultures have done and some still do.
I would call them extremists before calling them "devil worshippers" anyway.
The concept that sacrifice and rape are exclusively associated with Devil worship is a stupid and dangerous suggestion to make.
There are many people who worship, or work with, the archetypal figure of Satan who would never hurt a fly.
There are sick individuals from all walks of life, their religion does not make them do these sick acts, it is normally the case of mental illness, in extreme cases psychopathic tendencies- such as being incapable to experience empathy.
Not all devil worshipers hurt people or sacrafice them. Sometimes they do those things because that were what they were tought or learned. I worship him and i dont harm others.
It very much depends on what you mean by "devil worshippers".
There are some who would consider that anyone who does not practice Christianity are devil worshippers. Yet the vast majority of people in the world are not Christian and their practices do harm to no one.
There are those who practice Satanism. Yet many of them do not worship any deity at all, feeling that mankind is the highest form of creation. And there are those who look to Satan, Enki,Lucifer, or Set as deities and call what they do theistic Satanism. Neither of these sorts of "devil worshippers" include rape, human sacrifice, etc as part of their practices.
There are some who do practice such evil things. Think of Charles Manson for example. But they do not represent what most Satanists are like. These people are seriously mentally ill. They are as abhorrent to real Satanists as they are to the rest of us.
Like said they exist but not automatically associated with Satan that's just the stereotype we satanist get I mean I know many peaceful satanist cause the one I am and associate with believe satan Is our beginning and creator but we don't feel hate we are peaceful outside of self defense 9 of 10 times people who sacrifice people have an illness that's it