Why did he have to leave so soon?

a few months ago may 20 to be exact my dad died from lung cancer.he was first diagnosed with the worst kind on december 12 of 07. six months later he was rushed to the hospital cuz he couldnt breath. he got to the hospital and was in agonizing pain. the doctor put him on morphine so he fall asleep, he kept wakin up in more pain so they increased his morphine. he stayed asleep. i went home to my uncles that night to sleep, he woke me up at about 3 in the mornining. my pops ped away, i was shocked,scared,mad,depressed and worried for my stepmom. i moved from new york to georgia after the fact. my main queation is still why did he have to leave me so soon? he was only at the of 46 im only 16>WHY?