Why i cant accept losing so much?

when it comes to basketball.....in our league i hate losing so much but im not a violent person which when i lose in a match i usually throw the things i was holding no not like that but when i lose i feel so down on it even my parents says that "if you dont accept losing...you must quit playing" but my reason is there are no simple things when it comes to basketball all things must came from hardwork dedication on what im doing inside the court no simple things on it even you sacrifice your body.......but i really love basketball it fills enjoyment in my life as the matter of fact playing in the NBA is my goal in my life im just asking why do i have to fills sadness when i lose.....help me guys