Substance abuse is normally taken as using it so much that it causes risk of harm to yourself or others, and interferes with having successful family, work and social lives.

For example, my 2 years younger brother started smoking pot in high school, and had to be evicted from our mother's basement, with locks re-keyed, at age 60, for elder abuse. For more than 4 decades his life revolved around working just enough to collect EI the rest of the year to pay for staying potted all day long. He had traffic accidents while potted and used pot as a construction straw boss, trying to talk other workers out of drinking booze on the job. Doh!

Now that is what I would regard as a Pot Substance Abuse problem.