None. I don't like tobacco or alcohol much, I don't have good enough connects and the money to keep buying some stuff every day, and I also don't have the ability to conceal my euphoria or trippiness or the DILATED AS FUCK pupils. Finally, even when done in a setting away from prying eyes, many substances have negative effects like hardcore laziness and random eating, as caused by pot, or impulsivity, as caused by abuse-prone substances, or mindfucking, as caused by hallucinogens. It's my belief that every single drug is more appreciated when its usage is spaced out.