Other People's Opinions

I often read message boards on various sites and find one thing very interesting. It doesn't matter what the topic is, someone has something negative to say about it. Someone is going to get offended by what someone else thinks, says, does, believes, etc. And all it takes is for one person to stir the stink pot and it's Katey bar the door!
My question is a simple one. Why does someone else's opinion matter so much to some folks? I guess I wonder about this because other people's opinions rarely matter much to me. It is only those who have gotten close to me who may have opinions that might sting me, but the rest of the world can go pound dirt for all I care. Before I would allow some unknown person on a message board to get me that worked up, I'd leave the site and never look back. I know that's what I'd do because I've done it before--sometimes not as quickly as I should have, admitedly so. But I live and learn.
I've also come to the conclusion that folks who attack me for what I think have far more issues than the fact that they disagree with my opinion on the color of the sky or whether or not I encourage my child to believe in Santa or anything else. When someone attacks me because of a stated opinion, I remember a button I used to wear on my jacket in high school (in the 70's when buttons were the rage). It read, "Sounds like a personal problem to me." Their ire says far more about them than it will ever say about me. I figure that problem is their puppy and they can feed it.
Some folks are just too insecure with their own beliefs and opinions. Those folks see any difference as a personal attack on their lives. Those folks need to get over themselves! Form a support group for crying out loud! But leave those of us who are secure in our lives or are looking for answers out of their personal drama.
Just my opinion. Others may vary. Void where prohibited by law.