This is a tough situation for any parent.
I am sorry, I have just completed my response with recommendations to your request but the system got a problem and I do not see my response posted. I will try to work on it again.
I was saying how tough a scenario like this could be for any parent.
You stated you have other three older children who have not presented any serious problems like him. I was wondering how this developed, if it was a sudden change or took place gradually developing in several months or years.
Many times happen that changes like this are based on a person being deeply spoiled, what distorts his personality and leads to situations like this. Some children do react differently to spoiling and could not get this bad. I am not telling that this is his case, just speculating so to give a broader response here. Some people are much more predisposed to develop disorders like this after spoiling, a trauma or any other intense life event.
My best guess totally matches your fear, since it uses to be the case leading to behaviors this chaotic. The use-abuse of drugs could easily trigger mental health or behavioral disorders and most times it is not only one but a combination when people are this young. Again, some people could be predisposed to develop a disorder much easier and strongly that others under similar circumstances, and some could even develop psychotic disorders after a one time use of a drug.
First thing to do is to get him a drug test. From there you would know better what needs to be done. If setting boundaries and being consistent with consequences has not worked, then it is obvious something else needs to be done. He is old enough to be hold accountable for his actions, and he is not taking any responsibility here.
Any person who represents a danger to self of other could be reported by anybody and an intervention started leading to jail or treatment. Since he is still a minor, you have right to decide what is best for him, and that could be a very good thing here giving you the power to reach for help that would not be viable that easy if he happens to be +18.
You need to protect him from himself-ego-mental issues including drugs and your family, so it does make total sense to take action and get him this drug test and if you have to call the police for any violent-risky behavior do it. His ego would hate you but you would be supporting your real son and giving him the chance for rehabilitation.
He would need to go through detoxification program and then to intensive inpatient treatment. There he would be restricted and depending on how well the supports happen to be and his willingness to cooperate he would have more or less chances for rehabilitation. Then aftercare support and intensive outpatient become more challenging since most people do relapse, but you can only do your best on what you can control, and yes, you could end every form of support including housing if he continues to neglect and abuse self and others. It would be wise to get information about local state-county laws on this area.
Please do take immediate action with all the support you could get since your son and family need and deserve it.
Hope it helps.