Custom editor is not applying the settings.

I made a script that round the points of the polygon collider 2D:

 using UnityEngine;
 using UnityEditor;
 using System.Collections;
 
 [CustomEditor(typeof(PolygonPoints))]
 public class PolyColliderPointAling : Editor 
 {
     PolygonPoints polygonPoints;
 
     public override void OnInspectorGUI()
     {
         serializedObject.Update();
 
         if(GUILayout.Button("Run!"))
         {
             polygonPoints = target as PolygonPoints;
 
             PolygonCollider2D[] colliders = polygonPoints.gameObject.GetComponents<PolygonCollider2D>();
 
             for(int y = 0; y < colliders.Length; y++)
             {
                 Vector2[] points = colliders[y].points;
                 Debug.Log(points.Length);
                 
                 for(int i = 0; i < points.Length; i++)
                 {
                     Vector2 pointPosition = new Vector2(Mathf.Round(points[i].x), Mathf.Round(points[i].y));
                     points[i] = pointPosition;
                     Debug.Log(points[i].ToString("F5"));
                 }
             }
             EditorUtility.SetDirty(polygonPoints);
         }
 
         serializedObject.ApplyModifiedProperties();
     }
 }

The PolygonPoints script:

 using UnityEngine;
 using System.Collections;
 
 public class PolygonPoints : MonoBehaviour {
 
     PolygonCollider2D[] colliders;
 
     void Start()
     {
         colliders = gameObject.GetComponents<PolygonCollider2D>();
         for(int y = 0; y < colliders.Length; y++)
         {
             Vector2[] points = colliders[y].points;
             Debug.Log(points.Length + "pontos.");
             
             for(int i = 0; i < points.Length; i++)
             {
                 Debug.Log(points[i].ToString("F5"));
             }
         }
     }
 }

When I hit the "run" button the console shows that the points have been rounded. But when I hit play I lose all changes and I don't know why. How can I apply the changes that I have made ?