Is basement area more expensive than living area?

You can throw the laundry from the main bathroom down the chute from the upper floor or from the children's bathroom which is on the ground floor .... It always depends on the floor plan, many also have the chute simply in the hallway .... Laundry is thrown in unsorted, I then sort it downstairs in the basement by colors etc, because the kids unfortunately don't do it correctly anyway (depending on their age).

I don’t have a laundry chute, but at acquaintances’ places I noticed that all family members have to be very careful and must never throw in a damp towel/bath towel, because the other laundry items start to smell (we say minkeln) very quickly.

You have this problem everywhere. Damp laundry in a container or pile smells musty. Kids, better teenagers who don’t use the laundry chute, don’t put the socks away 2 doors down either.

Hello there,
I am getting into the topic and presenting you my planning problem:

We have a flat, 225 m2 "large" plot of land, on which according to the development plan we are supposed to build a single-family house. The house consists of a ground floor, upper floor and a recessed top floor (this is required according to the development plan) and has a maximum gross building area of 9x9m, so we are calculating with a living area of at least 150-160 m2.
The question now is whether we should build with or without a basement.

Arguments in favor:

[*]A basement naturally offers a lot of space, for example for building services, laundry, storage, etc.
[*]Without a basement we definitely need a building services room on the ground floor. With outer dimensions of 9x9 we could manage that, but we would prefer to use such a room differently (e.g. my wife is a teacher and needs a study);
[*]We will build a 10x3m garage with an extra room, which however will only be a maximum of 4x3m in size. Unfortunately, we do not have more space, for example for a garden shed or similar;
[*]We currently have only one child, but are planning for at least a second or even third. Despite this, space could become tight;
[*]higher value of the house.

Arguments against:

[*]The basement has to be built as a white tank due to the high groundwater level, which means:
[*]high costs, I am calculating at least €60,000-70,000 (usable basement, without or with hardly any windows);
[*]despite the white tank, I am still afraid of moisture, because for example the basement might be built incorrectly. A house with a damp basement is worth less than a house without a basement;
[*]The issue with additional children is of course uncertain. What if no more children come? We would have a huge house and hardly any use for it.

And so on and so forth...

I know, there are some, partly inconsistent (what if...) factors at play. Nevertheless, I would be very grateful for concrete and objective advice.

For better understanding, I am attaching the development plan.

We cannot take away your fear.

Thank you, I don't expect that either. I am rather hoping for experiences from other builders who may have been or are in a similar situation (small building plot, strict regulations, soil conditions, etc.) and how they solved it. However, I realize I probably asked the question wrong.