WHY ?

Why is it that some people never change ?  Despite telling them numerous times that they forget to do something they still continue to do so? It seems to me that either they do not hear or they are just plain dumb.We have been told that we should be tolerant but surely tolerance has its limits .We have been dealing with intelligent people , people with vision , with drive and who have a purpose in life and when we come across such dead woods it becomes something difficult to accept and tolerate.
Why is it that there are people who are so untidy , unkempt and yet expect to be given due consideration ? To me the measure of a man is the way he carries himself, his personality , his ability to communicate effectively with others and above all his manners.Why are there people who cannot even pause a second from eating when someone talks to them ?Why are there adults who need to be treated like children and sometimes even worse ?
Why do you need to told not to do certain things over and over again ? Are these kind of people suffering from mental defects or are they just plain insensitive to other people?
Under normal circumstances you will just want to avoid having anything to do with such people by staying far away from them .But under certain circumstances you dont have a choice  and you cannot help but try to be patient and as tolerant as you can be .We probably have to accept the fact that there are people who cannot change , who cannot see their weaknesses even when being told over and over again and that there are people who cannot even remember simple things or chose not to remember.
Why are there people who dont know how to even say a simple "thank you " when thanks are due.? I believe that such people are lacking and are in a world of their own and they are sterling examples of the saying " they have eyes but see not. they have ears but hear not , they have brains but think not , they have mouths but speak rot ".