The big advantage is that you can be sure that the cannabis you are buying is actually of a good quality. Especially in Baden-Württemberg (cannot find the source anymore), more cannabis that has been confiscated by the police was impure than pure. And you never know whether you get indica, sativa, 10% THC, 25% THC, CBD that is spiked with HHC, just CBD, or cannabis that is spiked with something else. If you find a good dealer that you can trust has good quality weed, than that is fine. But I have been buying from a lot of different dealers over the past few years (not random people on the street, people I know through other people), and the quality is always all over the place.
I never want to buy from any black-market dealer ever again, once these cannabis clubs are up and running.
This. Buying weed in Berlin is nothing like buying in pre-legalization North America. If you buy without a solid connection, you will more often than not get a laced product. It took me a few years to get a reliable supplier and people frequently reach out to me on Reddit because I brought it up years ago.
I never want to buy from any black-market dealer ever again, once these cannabis clubs are up and running.