The guys who try to tell you what you can or cannot do with your money. I didn't really pay much attention to them for the last 12 years or so while in Spain but being in Germany atm and having to re-verify some accounts I've learned that BaFin passed a law three years ago already restricting Germans (once again) from taking advantage of markets themselves. In this case the Bitcoin market.

Long story short, after doing a reverification of one of my accounts I lost margin access thanks to BaFin.