It is about power.
It is about asserting that power and making the person the power is asserted against feel weak, whether that weakness is physical or emotional.
And the attacker, the (let’s call him what he is) abuser, he (and it’s almost always a he) knows that the person abused may not, often will not, tell because they are ashamed, or guilty that they didn’t, couldn’t, stop it – no matter how old they are – or fear that they may not be believed, or fear that awareness of the abuse will hurt those close to them, or fear that by telling they will relive the ordeal, that by telling there are some who will take the opportunity to define them by what happened.
And if the person abused does not speak is it their fault? Are they responsible for everything after? Those who are quick to blame the person abused for their understandable silence appear oblivious to the existing guilt, the trauma, the way they live with the incident for months, for years afterwards.
And those moments of asserting power, those moments of violation, of violence are gone quickly. Does the abuser lie awake at night remembering? Does he lie awake revisiting the moment?