That’s a good question. I’ve never studied the topic, but your answer sounds reasonable. I did read over some relevant bits from Wikipedia

While the motivations for self harm vary, the most commonly endorsed reason for self harm given by adolescents is to get relief from a terrible state of mind.

Many people who self-harm state that it allows them to “go away” or dissociate, separating the mind from feelings that are causing anguish. This may be achieved by tricking the mind into believing that the present suffering being felt is caused by the self-harm instead of the issues they were facing previously: the physical pain therefore acts as a distraction from the original emotional pain.

Alternatively, self-harm may be a means of feeling something, even if the sensation is unpleasant and painful. Those who self-harm sometimes describe feelings of emptiness or numbness (anhedonia), and physical pain may be a relief from these feelings.

Those who engage in self-harm face the contradictory reality of harming themselves while at the same time obtaining relief from this act. It may even be hard for some to actually initiate cutting, but they often do because they know the relief that will follow. For some self-harmers this relief is primarily psychological while for others this feeling of relief comes from the beta endorphins released in the brain.[93][medical citation needed] Endorphins are endogenous opioids that are released in response to physical injury, acting as natural painkillers and inducing pleasant feelings, and in response to self-harm would act to reduce tension and emotional distress.