It served two purposes. The first was to eliminate him as a liability. There are undoubtedly many more people performing the service that he performed for the oligarchy, and whose profile is unknown. He needed to be eliminated.
But the second purpose … of the murder of Epstein was to send the American people a gigantic “fuck you!”
The whole point was to make it so obvious he had been murdered that everyone would realize it.
And to likewise make it clear that the murder could take place in a high security facility to a person under heavy surveillance … and nobody be held accountable.
This murder sent a message: “We can do what we want, when we want, to whomever we want … and there isn’t a damned thing you can do about it.”