Bottom line is: it's not always about you. I keep hearing these phrases: (1) "You always have to look after yourself.", and (2) "I have to look after number one." Sure, you do. But you can't always base everything on that. If you do, you end up being SELFISH. You'll end up ALONE.
Manners are learned early in life. But it doesn't mean that you can't learn them as you grow older. The only possible dilemma is that the person 'learning' only learns temporarily. If s/he is your friend, you usually try to talk to that person when s/he has done something improper or disrespectful. S/he may then try to change for the better. In a perfect world, you wouldn't have to tell that person every time s/he keeps doing it. Besides, how many times do you need to tell that person before s/he finally gets it??? Once should be enough.
Good-manners is usually linked to respect.
We say, "Thank you." We say, "Please." We don't interrupt. We don't argue. We don't fuss. We listen when people talk to us. We share. We clean up our own mess. We don't take things or people for granted. We make an effort in keeping in touch with friends. We always ask. Courtesy is important. We don't presume.
These are just a few things. I can go on but I think most of us already know these. To those who don't, I guess they'll just have to learn when their friends start avoiding them. Come to think of it, maybe some people just don't notice it. Yup, SELFISH indeed.
Rambling Gypsy