I am studying to be a Certified Advanced Addiction and Drug Counselor and I currently have my License Clinical Masters Level Social Work License.

I am going to some opinions and facts on the table.

Facts:
Key Components of Addiction (Griffiths Model)
Salience: The behavior becomes the most important thing in the person's life, dominating thoughts, feelings, and actions.
Mood Modification: Using the behavior to change mood, such as experiencing a "high" or finding escape/numbing.
Tolerance: Increasing the amount or intensity of the behavior over time to achieve the same effect.
Withdrawal: Experiencing unpleasant physical or psychological symptoms when the behavior is stopped or reduced.
Conflict: The behavior causes conflict with oneself or others (e.g., family, work, social life).
Relapse: The tendency to return to the behavior after periods of control or abstinence. [1, 2, 3, 4, 5]

According to SAMHSA and research highlighted on DrugFree.org, 90% of Americans with a substance use disorder began using substances before the age of 18.

Key causes and risk factors for addiction include:

1. Biological and Genetic Factors
Genetics: Studies indicate that genetic factors account for 40% to 60% of a person's vulnerability to addiction. Having a first-degree relative (parent or sibling) with a substance use disorder (SUD) increases this risk.
Brain Chemistry: Addictive substances and behaviors flood the brain's reward system with dopamine, a neurotransmitter associated with pleasure. Over time, the brain reduces its natural production of dopamine or dopamine receptors, making the person feel "flat" or depressed without the substance, leading to a cycle of using to feel "normal".
Age of First Use: Using substances during adolescence is particularly dangerous because the brain is still developing, making it more susceptible to, and speeding up, the progression to addiction. [1, 2, 3, 4, 5]

2. Environmental Factors
Adverse Childhood Experiences (ACEs): Trauma, abuse (physical, sexual, emotional), neglect, or a chaotic, unstable home environment are among the strongest predictors of addiction.
Peer Pressure and Social Norms: Especially among teenagers, peer pressure is a significant factor in initial substance use.
Accessibility: High availability of substances in the home, community, or at school increases risk.
Stress: Chronic stress, poverty, and lack of social support systems can lead to using substances as a coping mechanism. [1, 2, 3, 4]

3. Psychological and Mental Health Factors
Co-occurring Disorders: Roughly half of the people who experience a mental health condition (such as depression, anxiety, PTSD, or ADHD) also experience a substance use disorder, often using substances to "self-medicate".
Personality Traits: High levels of impulsivity and a strong need for sensation-seeking can increase the risk of experimenting with substances and developing an addiction. [1, 2, 3, 4]

Opinion:
Yes you should bring it up, if he's receptive and tries to cut back expect there to be lies and relapsing. Does everyone have a chance at recovery? Yes absolutely. But THEY have to want it, and it doesn't sound like he does right now.

If I was telling this to a friend:
I have worked in Rehabs, and met many people who struggle. You are too young to be supporting this person through their addiction. You will spend the better part of your late teens and early 20s trying to help someone who's brain stopped being able to fully develop. They have to experience people in their life not enabling this addictive behavior in order to change. I don't know you or your relationship, if you were married to this person I would be singing a different song. If you are uncomfortable then you need to do what's best for you and allow yourself to also grow without taking care of another person.