One big difference is that heroin is mostly illegal or, if not outright illegal, decriminalized for personal use. Gambling is legal in most places, can be advertised quite freely and restrictions can be easily circumvented with crypto. Crypto casinos have little to no age verification and typically operate extrajudicially (from the victim). Gambling addiction has a high outcome of suicide and tends to leave financial ruin affecting not just that person but their entire family.

Heroin addiction was largely created by the criminialization of cannabis (the first so-called War on Drugs under Nixon) as a tool to persecute black people and war protesters and the overprescription of opioids (eg the Sacklers/Purdue).