Well, German BUND 10y rates at -0.8% pa. right now sound to me like the worst way to spend or invest your money, today. A boatload of risk and not even a return. Woah!
Dont get me wrong, this is no advise and maybe they manage to make -4% possible and it moves on, but I have doubts. Just my 2 cents.
By the way, is it called an investment, when return is ex ante known negative? I would NOT call it investment but spending. A fee for being part of the club, every year 8 EUR per 1'000 EUR. Take your madame to the cinema, instead. This alternative way of spending the money could possibly become some fun in the end.