Cocaine triggers a dopamine response (simplified, I dated someone with an addiction). Is that a positive impact? Moderation is important, as in reflection as to why you’re enjoying something and if it's healthy.
If cocaine was free I think it'd have a tremendously positive impact.
Maybe with robust social safety nets and mental health services available (Portugal model).
cocaine was cheap and easy available a century+ ago (for example the original Coca-Cola was an over-the-counter headache treating mix which contained alcohol and cocaine). Didn't lead to much positive impact. (Note: i'm for full unlimited legalization, though not because it is that good, it is just that 1.the adults have the right to practice Darwin theories and 2.the Prohibition is really bad)