Despiseth his own soul - That is constructively; for if the instruction lead to the preservation of life and soul, he that neglects or despises it throws all as much in the way of danger as if he actually hated himself.
SDA Bible Commentary (limited)
Volume 1-7
32. Despiseth. Those who refuse instruction are careless of their life. The issues at stake may appear small, but every decision affects eternal destiny (see ch.8:36).