The simple fact is, nuns and priests are arrested adolescents.
They never mature into adult thinking, and the reverence with which they are worshiped simply adds to their immature view of the world, and a seriously under-developed sense of right and wrong.
When priests know that if they dropped their cassocks and dumped on the carpet, the woman of the house would say it was good for the pile, it's a very short step to thinking you can do exactly as you please, to whom you please, and no-one is ever going to tell you that you are wrong, and you need to stop.
That of course is facilitated by church's habit of simply relocating an abusive priest when it can no longer pretend that he is being a normal human being actually fulfilling the role it has placed him in.
I don't say that all priests become abusers, of course they don't but the utterly unnatural life they lead, coupled with the adoration they are offered, and the tacit support in their deviance by their employers means that the church is an abuser's playground, and the church is completely responsible for creating and sustaining that system to this day.