Plenty of drugs (the msot fun ones tbh!) are non-addictive. LSD and Mushrooms in particular are nearly impossible to get addicted to. First off your mind really wants a break after doing them, they can be very intense experiences, and are also mentally and emotionally draining. Second, they both build tolerances extremely quickly, I dropped acid 3 days in a row at a music festival once. Did 1 tab day 1, 3 tabs day 2 to get around the same effect, and over a dozen (honestly lost count) and still didn't trip as hard as day 1 or 2. Receptors in my brain just weren't having any more of it at that point I guess. But yeah, if addiction is your only concern and you aren't worried about the legality, etc., psyches are a good choice.