Zaroff's great hubris seems to be borne directly out of his sense of himself as an educated man. He is willing to believe that he is above others in terms of human value and this leap of moral reasoning seems to be a symptom of his belief in his cultivation, enculturation, and education.
Education is what you make of it. The most evil minds in the history of the world have been intelligent and educated. Many people take what they learn and twist it to their liking. Great minds especially have the capacity to use information in a self-serving way. Education is supposed to make one sophisticated, not only in decorum, but in the way you treat others. Education is what makes civilizations prosper. Zaroff is not evil because he's educated. He's evil because he manipulated his education to justify a lifestyle and form of entertainment that he sought.
The main point is to unsettle the reader, I believe. There is an irony between Zaroff's civilized persona and what he does. This irony is continued throughout the story. For example, the ending is also ironic because Rainsford kills Zaroff in cold blood after the game is over and he is no longer in danger. Or is he?
I think the author goes to great lengths to describe Zaroff as an educated and urbane man to heighten the disparity between his mannerisms and what he actually does - to have a man who is as cosmopolitan as Zaroff who at the same time argues that he is able to hunt down other humans as prey or game clearly emphasises his barbarism.
General Zarroff's education served a very large purpose in the short story "The Most Dangerous Game." He was cultured, cultivated, and civilized, but his thinking and his way of life was truly barbaric. The contrast with his educated self and his true self is crucial to the story.
General Zaroff is educated and cultivated on the outside. On the inside, though, he is a barbarian. He drinks fine wine, wears tailored clothes, listens to opera, eats fine foods, and lives in a lovely house full of treasures--including human heads which he hangs as trophies on his wall. This dichotomy (split) between what he seems to be and what he is makes the story intriguing and interesting and even appalling. The contrast between Zaroff's cultured outside and his primitive inside is one of the major themes in this short story.
In Connell's story, the education, training, and cultivated tastes of General Zaroff have reached the point of surfeit. Because he is in a jaded state, the general seeks some diversion that will relieve the ennui in which he finds himself. And, since he has satiated his senses already, there is nothing that intrigues him but the hunting of an enemy on the same level as he: man, "the most dangerous game."
Indeed, the experiences and exposure to the finer things in life, as well as the development of his sadistic mind serve a veritable purpose to the author as they are what drives General Zaroff to create his bizarre and sadistic game.
I am not completely sure as to what you mean be "serve true purpose. I suppose the answer to the question depends largely on what you mean by this.
To me again, the true purposes of education are twofold:
- To make people technically skilled -- to make them able to do things that benefit them economically.
- To make people more "well-rounded." In other words, education ought to be able to make people more aware of morality and ethics and how one should act towards others.
If you accept these two purposes, Zaroff fulfills the first but not the second. He has clearly become technically skilled -- enough so that he has gotten rich enough to create this island hunting ground for himself. On the other hand, his moral and ethical sense is clearly not developed. If it were, he would surely not hunt people.
So, the answer depends on what you mean by "serve true purpose."