The point was gangs are dynamic. The rackets come and go but the gang always finds the ways to make money. True organized crime is always a diversified business. The Russian Mafia sold Soviet nukes and subs during the 90s for Christ's sake.
There may be other sources of income, but the drug trade is a cornerstone in organized crime and to eliminate it would seriously hurt gangs and other organized crime groups.
Heroin and opiates in general cause no damage to the brain unlike crack, coke, and meth. The only damage heroin does is to peoples lives who are addicted to it, the addict lifestyle can be damaging
the danger in heroin is u cant trust street heroin, but it really is almost identical to morphine, if someone had say pharmaceutical grade heroin, clean syringes, chipped with it not shot up 5 times a day. Then yes its believed to be quite safe its all a matter of the quality and the users ability to judge there tolerance. i read a very well researched article on the safety of it a while back, and it said the junkie lifestyle is really what makes it dangerous, it even mentioned that a founder of Johns Hopkins was a morphine addict for a very long time and died a natural death with nothing wrong with his organs and what not on the autopsy, and like a said above morphine and heroin are alot alike. Ive heard the only real problems come from the way it effects your brains ability to perceive pain making it more intense, and its effects on the brain are even less than that of high doses of oxycontin.
the problem is you only know how you will respond to drug after you try it for the first time. As long as you know the risks i say fuck it do what you want its your life. Me personally with a uncle who has schizophrenia even something as tame as weed i currently wont try because it isnt worth the risk.