Why do I always show off all the time?

I'm 13 years old and live in a well off household and get stuff without even really asking for it.

I have a lot of iPhone (3GS to 5S and 5C), galaxy note 3, all of the iPads except the first iPad Mini. 2 gaming computers with SLI'd graphic cards (the 2nd one was given to me by my older brother who own a large computer shop) I have a grand piano in the living room which was bought for me when I was only 4, 3 guitars (one which is supposedly rare, I'm not sure my dad collects antiques and rare stuff) I have a large television in my room (I guess every kid does though) a PS4, 3DS, PSVita, PSP, Wii U… Remember this is stuff I don't ask for, my parents just know me well.

I have a few good friends, I'm not popular but I get on with everybody I meet. I live in a 'perfect' household (parent are still together, I have and older brother and a younger sister and we never fight) my parents have never faced bankruptcy or have never been harmed financially by prior recessions. I have good grades and have always completed tests with top marks…

I have all this stuff yet I feel like I must show off. I always mention the price of items even though there's no reason to. I always say how much money I've got with me… You know just showing off. Like I need to explain to everyone how easy my life is. It's pathetic, and I know I need to stop but there must be a reason as to why I do this.

Please help or explain to me. I would greatly appreciate it.

You are 13 and most likely in middle school, which is a weird place. You want to show off to make people jealous, I did it before.

MY DEAR: AT 13 YEARS OLD, THAT'S WHAT YOU ARE SUPPOSED TO DO… BE THE LIGHT AND SUNSHINE IN
EVERY GATHERING. BE THE PERSON THAT MAKES EVERYBODY LAFF AND GET OUT OF THEIR DOLDRUMS…

DON'T YOU KNOW THE GREATEST COMEDIENNES WERE KIDS
ONCE WHO JUST "SHOWED OFF, BUT COULDN'T Help IT";.;
THAT'S ALSO CALLED: "BEING AN EXTROVERT" OR BEING THE KIND OF A PERSON WHO IS ALWAYS THE CENTER OF THE CROWD… THE JOKESTER, THE FUN PERSON… WHAT WOULD WE DO WITHOUT YOU, THIS WOULD BE A VERY BORING WORLD…

LIGHT UP YOUR LIFE AND EVERYBODY ELSE'S! GO FOR IT AND WHEN YOU ARE ON TV… TELL US WHAT STATION AND TIME CAUSE YOUR KIND OF PERSON ALWAYS ENDS UP IN A SPOTLIGHT SOMEWHERE… BE HAPPY!