this and this wrote:
Its the same reasons you will see fat out of shape slobs show up at an easy 20 mile group bike ride decked out in $10k worth of bicycle and gear.
1) they believe it will help them go faster.
2) they may not have the time/ambition to train more, lose weight, etc. but they have the money to buy the best gear.
3) they believe owning and using the best gear helps project a certain status.
If it bothers you that they do this, run races in old T shirts, cut off cotton sweat pants, and thread bare 20 year old adidas shoes. Dust those people. Then jog back out on the course so they can see what beat them,
I guarantee those people don't care what you wear. It's only people like you and the OP