If this is true (and I don't know one way or the other) how could he get away with it for so long? It would seem that after the first couple of people were blackmailed, the word would get out and everyone would start avoiding him. The world of big time powerful movers and shakers is a small world.
Epstein never planned to blackmail any of his clients. As you say, that would be counter productive. The reason he had video of the clients acts were to ensure no one ratted on him. Anyone doing so would draw the wrath of all the other clients as they would all be exposed.
Epstein provided a safe location where rich and powerful deviants could party down. As a result, they were eager to do him favors.