One thing that bugged me in Harry Potter was how, in book 3, Hermione needed a time-turner to attend all the classes. The time-turner being a secret device that most people didn’t even know about (and for good reason). If I remember correctly, McGonagall had to go to quite great lengths to persuade the Ministry od…

But they do teach it at Hogwarts at some point. And even if not all students get to that level in Potions, let’s assume the majority of them do. And even if they don’t have the skills to brew it, they would know people who would, friends. And besides, I’m sure the wizarding world has a black market that would sell…