When you get older you will realise that you have to deal with people like this your whole life, don't judge him by the clothes he wears or how his parents live, that's just wrong to begin with.
So what if he isn't as gifted, and lucky as you, it isn't his fault.
With regards to him talking behind your back, bare in mind '100%' of the time is most likely an exaggeration; but regardless, just confront him. Tell him you don't have a problem with him, and if he would stop talking behind your back you would appreciate it.