>>987177If you stop using shampoo for ~2 weeks and wash only using water, the natural oil your scalp normally secretes called sebum (which is what makes animal fur soft and shiny though they don't use shampoo) will regenerate. Shampoo washes it away and makes you dependent on buying more shampoo to achieve what sebum does naturally.
The only downside is that those 2 weeks are miserable, as your hair will get really stiff and gross until your sebum levels are back to normal.
