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Essentially, people bully because they want to feel good about themselves. They want to see themselves being more superior and powerful by abusing others.

What you could do is just ignoring them. Once the enticing factor is being taken away, bully won't be able to get what they want, therefore they will then just stop trying.

Blocking and reporting should be good enough.

I think this case is really complicated to answer, first of all it can be anywhere. Usually it occurs dues to differences in perceived status. The best way I think to handle this is to seek some help. It may escalate. If those cyberbullies are people who we won't get to meet, we'll just have to either switch platforms or change to another personality but before doing that seek help to have some healing done first.