I am 23 years of age and am really a wealthy man by the grace of Almighty. Generally a person can have many evils in him but there is one evil that I hate truly in myself and I want to get rid of it. That is I think of others as of lesser degree than me. I look upon them as despicable. I have loads of jealousy in me especially from a person I find trying to have equal wealth than me though I do nothing to harm or stop that person from having it but I don't like it.
We all have weaknesses in our soul and some of us are not even aware of their weakensses. It is great that you are aware of a weakness and that you are trying to do something about it. May the Almighty give all of us the same blessing.
Everything that we have and everything that we do not have and like to have are part of the challenge (test) that we are facing and the only goal of this challenge is for us to try to be good enough so that we may deserve the blessing and mercy of the almighty in the hereafter and go to heavn instead of hell.
You are facing one of the aspects of this challenge and I pray to God to help us to come out of our challenges succesfully at the end.
I suggest you try a few things:
1. read verses 28:76-84 carefully and ponder over their meaning and reflect on them.
2. for every kind of wealth and comfort that you have and you will be having in future do Shukr (Thanks) to the Almighty.
3. pray for those who you feel you have ill feelings towards them and ask the Almighty to bless them and to give them and you the best in this world and the hereafter.
4. every now and then visit grave yard and think about those who have passed and the fact that you will join them one day (like the rest of us). While doing this think about the concept of this world as it is introduced in the Qur'an, that is, it is only a challenge (test) for us and that the materialistic aspects of this world in the wording of the Qur'an is nothing but playing and amusement. Think about the fact that when death comes no wealth will remain with us any more and that all that stay with us will be our deeds and behaviour while we were living and their effects on us on the day of judgement.
5. give a lot (within your capaciy) to charity and as much as possible anonymoulsy.
Technically speaking, you are not comitting any sins as you are not harming others, however you will have a much healthier and much more purified spirit if you try to get rid of the feeling and the thoughts that you described.
I hope this can help you and please pray for us as well.