Yes, 100%. Fancy rehab clinics are there literally for this reason. The Betty Ford Clinic was a punchline for a long time as being a brand-name Hollywood-friendly rehab that specialized in keeping their client list quiet. The kids of wealthy people can and do get addicted to drugs - cocaine in college would be an easy one.

I agree that it’s entirely unrealistic that a dealer would kill a family over money. A dealer would sooner blackmail the family, or threaten to harm the kid via “some associates.” If the dealer kills the family…how would they get money? The point of leveraging fear to get paid is that 1) someone needs to remain alive and afraid of something worse so they have a reason to pay someone to stop things getting worse, and 2) sending a message that other people will see that someone needs to get paid or there will be consequences. Plus, any drug-addicted 20-something will crumple up and be totally useless in this situation, rather than get sober AND get revenge.

Just throwing an idea out there - let’s say 20-something guy has a younger sister So we have 20, Dealer, and Sister for your setup. Maybe Loved One is a family member with skills the parents don’t have. 20 owes a ton of money to Dealer. 20 goes to Dealer’s place trying to score something and is already messed up and Dealer is about to throw them out, but 20’s phone rings. It’s Sister sending a message. Dealer gets interested, steals 20’s phone, and starts to run a scam on Sister. Dealer get Sister into way deeper shit. Parents are useless and have no idea what to do, but cut off money to both of them. 20 goes looking for Sister, who is found dead from an OD. Or ODs and goes to a hospital, but is pregnant with Dealer’s baby, or mangled in a car accident where Dealer was driving and Dealer was fine - whatever you want (please don’t get too misogynistic with it). 20/Loved One goes after Dealer for revenge, but it makes more sense for 20 at minimum because we’re invested in 20. You can only add Loved One if you introduce them as somehow “better” than 20, and more skilled.

Simply getting cut off from money is a pretty trite reason to get revenge because it will seem like it’s only about money, not the emotional connection with the family. When you add the Sister as the catalyst, 20 will feel guilt over being the way that Dealer gets their hooks into a family member, the parents will be helpless, so 20 or someone else will feel the need to act since no one else can. Though, this might be a very done to death plot.