Sports is not considered activity anymore.
Noun/verb agreement please.
Whether itsit's golf or football , itsports can be watched live by millions around the world.
I don't know if it's a rule, but since you use a pronoun in the dependent clause "Whether it's golf or football," you should have the antecedent "sports" (or "athletics" or whatever) in the independent clause.
I believe this idea is prevailing in American sports. Due to which every now and then we observe aggressive and unethical behavior of players.This philosophy prevails in American sports, manifested in frequent aggressive and unethical behavior in players today.
The reader knows that you "think" what you're saying, so I don't think there's a problem with just asserting your belief without the disclaimer "I think," which can weaken your statement. The second sentence was a fragment.
Arguing with referee is also seen during matches, interesting enough this is only when the decision is against the team or player otherwise they dont care what is fair and right.
This paragraph doesn't flow with the rest of your essay; it's in the middle of nowhere, and while it's supporting evidence, it isn't expounded on well enough to deserve a whole new paragraph.
There are more grammatical errors that you should weed out. But in general, I think you may be just grazing part of the prompt, which asks you to tell why you feel this particularly philosophy is prevalent today. You almost mention it when you say "this kind of disruptive behavior come up when winning is all you want," and you have a wonderful platform to begin this discussion with the story of Alex Rodriguez, and his "enormous pressure to perform and to prove his worth."
Your last paragraph tell us what you'd do to change this condition, but that isn't asked of you in the prompt. I'm not sure whether or not you should keep it, though. But I am pretty sure that if you devote as many words as you do exposing the prevalent philosophy to telling us why this condition exists, your essay would meet the prompt better.