I think this is the biggest factor. Ambitious people who want to become rich do not have any opportunities in Germany. It is good for people who are content with a middling but comfortable life. That's why most ambitious people leave.
And with the offer of DE citizenship where you're not giving up your birth citizenship, most people will take it, and move somewhere else in EU with a shiney new DE passport.
Just curious how well does that work? I assume it’s being able to have a job, have a place to live, travel once a year. Medical care not tied to employment but hopefully easily accessible?
So for most middle-class families, the work grind will continue for the rest of their life, until retirement (if it even exists by then), without anything to show for it (owning the place you live in). How are people even going to be able to pay for their rent between retirement (67 years old) and assisted living (+75 years old)?
A small town where I've lived was very much like its neighbours, but one particular neigbour was different in two clearly visible ways: ① there were (still are) more rich people in that neighbour and ② it was much easier to get financing for starting and growing companies in that neighbour.
Don't worry, wealthy people manage fine in Germany and multiply their capital.
It's just a glass ceiling on a middle class.