Y cant i write a good rap song and how can i?

i love rap i try to write my own lyrics but every time i think i have a break thru it always sounds extremely similar to sum one else's lyrics like too close to tell ne1 about cuz they wuld say i copied sum1 and when i have sum good lyrics some body else comes out wit sumthing very similar and i dont have very many experiences like the rappers have because no ordinary person has the parties or the women like they do and im not from the ghetto so i cant say how had my life was growin up but i dnt wnt to give up on it n im black either (tht was not a racist comment) so tht eliminates alot of things to tlk about. i also have a writers block so can sum1 give me some advice