The big wish-list package won’t be available for my children either, but I believe that their father and I should support them enough so that they can study properly. That means food, a bit of social life, and a room in a medium-sized city should be covered. For extra luxuries, they can work. I’m not paying for Munich, their own horse, or the year-long trip around the world.
PS: 400€ single apartment in Jena? Maybe in a block, otherwise by now you’d probably get a shared flat room for that... Maybe one of them will stay at home... But I have to plan so that another, “normal” study location (not Munich) is possible if the travel bug strikes. Otherwise, Jena also offers many opportunities.
I think the children can definitely come to terms with such a compromise if there is a good relationship. I would also at least encourage them to find a part-time job. It would be great if it fits their field of study. Beyond that, the support should be such that the studies don’t suffer, possibly even increase during certain phases. That is at least the perspective.
Maybe I have underestimated Jena a bit; when I studied for the first time, there were still some places that weren’t quite so expensive. Jena, Greifswald, and some other East German cities were always the target.
Anecdote: We rented my apartment with one other person for 460€ warm (2004). Funny enough, I saw a current listing for it one or two years ago. Meanwhile, the 2.5 rooms have become three rooms and the rent is 850€ cold.