Even assuming your observation was universally true (which I doubt, I firmly believe people can irreversibly deteriorate) - there are circumstances that can prevent you from reaching people. To name the immediate two that come to mind:

• lack of "alone" time that they will spend with you due to family / spouses / jobs
• you simply do not find the key (again, assuming it exists) to "peel back" their layer of anger and frustration that clouds their objectivity