It seems those type of people brag a lot about themselves, what they've done and how well they did it! It is sad, they don't realize that they should just be themselves, and people respond to them so much better.
I believe that sometimes it can. Some people want to get some attention, respect, praise or even more income and believe that by bragging or showing off that they will get what they desire more easily or quickly. Often, once the show off attitude has been revealed the person bragging destroys any trust and faith others may have had in them making getting what they desire much harder if not nearly impossible.