There's many reasons people talk behind your back; I'm only going to give you 3 of them. 1. They can't reach your level. 2. They can't have what you have. 3. They feel threatened.
The more people talk behind your back, the more often you are on their mind. People that talk behind your back is because they feel threatened of your success. They talk about you with hopes that others won't find you, so appealing. Once they realize that hating isn't working that will start telling lies. Haters don't really hate you, they hate themselves clearly because you are the perfect reflection of what they wish to be. Since they can't kill your dreams they will kill your character. You don't have to care that they don't like you. It is not your freaking problem. It is their fkng problem.