Hello,
we are doing that too... I am still under 50, but my husband is over. We are building bigger than now, but have planned our area completely on the ground floor and very spaciously. Both children are still at home, and that will probably remain so for a while. In our building area, there are some who already have their children out of the house and are building new again. Why not?
By the way, we have already earned our first house ourselves, without inheritance or support from parents or the like, and it is the same with the second house. I am not building this for my children; if they want a similar standard of living, they have to do something for it.