I have a lazy eye since i was 4 years old. im 21 now. and my rigt eye drifts outwards. when i visited the doctor he said if i were to do a surgery it will be for cosmetic reasons. is it worth to do the surgery? what will be its success rate?

Varies: After long term "lazy eye" the brain generally turns off the camera like input that gives it a blurred or double image. The longer that has been in place, the less likely aligning the eyes will restore vision to that eye so surgery is cosmetic, If the re-aligned eye does not function normally to maintain tracking, it may drift away again over time. The eye surgeon can give you current success rate