Can illegal drug abuse lead to killer diseases in the long run? will the government pay for care?

Even legal drug: Abuse like alcohol or cigarettes can cause lethal problems. So far, insurances, whether public (medicare or medicaid) or private, like blue cross do cover. But no one has a crystal ball about what insurances are likely to do in the future. Insurance companies, after all, are in business to make money.

Yes/Yes: Iv drug abuse and needle sharing leads to acquiring hiv. Yes your care is paid for. That said, don't do it.