Moving the points of a polygon collider to form a wave surface 2D

I wrote this code to get the top points of a polygon collider and move those points. I can get the points but I can't move them, wich is wierd because I can move them if I edit them in the inspector(while playing). What am I doing wrong? Is there another approach to this? The end goal is to have a 2d water surface where a surfer can surf on. I put in the OnDrawGizmos to see if I truly get the right points.

https://snag.gy/fwsvA4.jpg

using System.Collections;

using System.Collections.Generic;

using UnityEngine;

using System.Linq;



[RequireComponent(typeof(PolygonCollider2D))]

public class Wave2 : MonoBehaviour {



    private PolygonCollider2D polygonCollider2D;

    private Mesh colliderMesh;

    private int[] indexesOfTopPoints;

    private AnimationCurve curve;



    private void Awake()

    {

        polygonCollider2D = GetComponent<PolygonCollider2D>();

        float lowestY = polygonCollider2D.points.Min(x => x.y);



        indexesOfTopPoints = polygonCollider2D.points

                            .Select((p, i) => new { Point = p, Index = i })

                            .Where(x => x.Point.y > lowestY)

                            .Select(x => x.Index)

                            .ToArray();



        for (int i = 0; i < indexesOfTopPoints.Length; i++)

        {

            polygonCollider2D.points[indexesOfTopPoints[i]] += new Vector2(0, 50); 



        }

    }



    private void OnDrawGizmos()

    {

        Gizmos.color = Color.red;

        for (int i = 0; i < indexesOfTopPoints.Length; i++)

        {

            Gizmos.DrawSphere(polygonCollider2D.points[indexesOfTopPoints[i]], 0.1f);



        }

    }

}