The substance use/abuse part can be treated. However, in order to have a successful life, recovery is necessary. Recovery may take many forms but the 12 Step Programs do a very good job for those who are sincere.
Without any kind of recovery, too often the substance abuse is substituted by something else. One person I know, who stopped drinking when a family member was killed, spent his way through one-million dollars buying frivolous things. Every time he got the urge to drink, he went shopping.
People who have abused substances and want to live clean and sober need to do more than just put the substance down. And, even those who go into recovery do so with varying levels of success. There is an expression in the Recovery Movement, "some people are sicker than others."