How can i create/instatiating GameObjects of ThirdPersonController by script in c# ?

I want when running the game to have like 20 ThirdPersonControllers walking. Today what i did in the Hierarchy i dragged two ThirdPersonControllers and when running the game they are walking.

But i don't want to drag now another 18 of this in the Hierarchy. How can i make it with a script ?

What i tried so far is in the Hierarchy creating new empty GameObject and in a new c# script in the Start function i did a loop and then draged this script to the empty gameobject but when running the gam my whole pc frozed and memory was on 100% i had to reset my pc. This is the script:

 public GameObject prefab;
 public int numberOfObjects = 20;
 public float radius = 5f;
 
 void Start() {
     for (int i = 0; i < numberOfObjects; i++) {
         float angle = i * Mathf.PI * 2 / numberOfObjects;
         Vector3 pos = new Vector3(Mathf.Cos(angle), 0, Mathf.Sin(angle)) * radius;
         Instantiate(prefab, pos, Quaternion.identity);
     }
 }