They don't want it to work well. The worse the situation is for the average citizen the easier they are to be influenced by propaganda as most people tend to look for a strong leader in times of need.
A previous spokesman of the AfD is on record saying that "the worse the situation for Germany the better it is for the AfD"...
Not only that, if there is one country that is most essential to the EU and where the EU is most essential to its success, it's got to be Germany. The whole idea of Gexit makes no sense and is entirely carried by fee-fees.
Only if you assume the plan is meant to benefit the country. If you assume that they want to profit from the suffering it makes more sense. Irrational, cult-like mindsets are easier to peddle when people are miserable.
I think they are definitely malicious, but I don't think they are capable of such cunning planning. They yearn for the Germany of the 50s and 60s and that means, among other things, no EU.
I don't think they yearn for any time that actually existed in the past. They yearn for a simpler world, one where people all have the same skin colour, sexual orientation, religion, life goals,... and where good things happen to people like them and bad things happen to people who are different.