How to taper shader displacement?

[thinsoldier]

I’m trying to figure out how to get this shape with shader displacement only:

(precursor to figuring out how to do the same in geometry nodes later)

I can’t figure it out.

I thought I could use the z position of the geometry as input and then float curve adjust the z value.
Where z is zero, scale to zero. Where z is 1 scale to zero. Leave the middle values alone.

This approach does not seem capable of giving me the desired shape.

[Okidoki]

First of all i think you wanna change the object so you should use texture coordinates object and then maybe: