because, and hear me out, it is completely meaningless.
you have apparent skill and a solid understanding of linework. you did that drawing as what, an exercise? character design? perhaps just because you were bored. the guy is purposeless though. it's just a portrait, and not a portrait for the sake of being one either - it's just a face. it's a well made face, but it is not something to be pondered for a long period of time. no one will look at that visage for hours and wonder about it.
there is no story. there is no background. there is no vision here. it's merely good linework; another page in a sketchbook of inconsistent styles, ideas, and thoughts, that'll someday be shelved when it's full, another blank sketchbook taking its place.
with your skill, you should now be defining the things most dear to you. whether it is a story, a masterful illustration, a character you long to bring to life. that is where fulfillment lies. and it lies in greater detail, and you know this i'm sure, than that man. there is ichor and soul in something that you truly desire to bring to life. that picture? merely a display of understanding what you are doing.