Middle Child Syndrome

I'm scared that my youngest is going to have middle child syndrome when our 3rd is born. Mostly because of two "middle child" adults we know that are strikingly similar to this description. One that is a friend that always jokes about having middle child syndrome and laughs about it (she said it was okay to mention her). And the other is a relative that doesn't seem to realize he has it and my husband says that is worse. I read about it today and this is what I read:

The middle or second born child often have the sense of not belonging. They fight to receive attention from parents and others because they feel many times they are being ignored or dubbed off as being the same as another sibling. They often look at everything as a competition between siblings. They will have a tendency to compare their lives with the oldest sibling and will often become jealous of that child. Being in the middle a child can feel insecure and often seek out the attention of their parents more than the other children. The middle child often lacks drive and looks for direction from the first born child.

They are not over achievers and just simply work enough work to get by, and typically that goes with school as well as a career. They often start several projects but rarely keep focused long enough to finish a project. The best career move for a middle child would be along the lines of using their creative. Going into a writing or journalism career, and into a career that they could freely express themselves would be good. Anything that would have hours that are flexible, and projects that frequently changed would be good for a middle born child.

I'm scared! I highlighted the parts that are the scariest to me. I am always hearing parents say, "My child has middle child syndrome" or "He is so attention seeking, he must be a middle child". Do parents just say these things or is it really true? I guess we'll find out soon!