I am a recovering heroin addict ( well tbh my addiction was more opiate pain pills such as oxycontin but i moved onto heroin for a while) and people used to say the same about me. I always looked after myself and made an effort with my appearance, i didnt have the financial worries that most people with addiction have, and i was able to keep it a secret from people. Opiate addiction is rife and a lot more common than people assume. There are 'professionals' who have opiate addictions, and i mean people in medical professions, top people in business etc. Personally i think when people can afford the drugs, dont engage in criminal activity to finance their addiction, they go unnoticed as they dont look like the stereotypical 'smackhead'. And that was the same for me too. I was naive and also thought of myself as a 'functioning' addict, but the truth is i wasnt at all. I may have looked like i was functioning but inside it was torture for my mental health.
Yes i totally agree, and i have just wrote a comment saying something similar as that was my personal experience with it