The adult moths do no damage. The larvae do, and they feed on protein fibres rather than plant or synthetic ones, which is why wool and cashmere suffer while cotton and polyester do not.
The key fact: larvae are drawn to soiled fibre far more than clean fibre. Sweat, skin oils and food residue are what make a garment attractive. Storing everything clean is a more effective defence than any repellent.
Also effective: breathable containers rather than open shelves, cool dark dry storage, and cedar or lavender. Mothballs work but leave a smell that does not wash out.