nasus is so broke

just played a game i was gnar into nasus no matter what i did he would just Q his way back to full health with his life steal passive. why does this guy not have to build one damage item but late game he just 1 shots me because all he does is farm. i did 13k damage and did not get a kill because if i got a gank he just ulted and ran away. he only did 9k damage but won lane because he is so broke