You can't refute opinions. That's all this is. Just because you disagree and claim to refute what Isay, doesn't make it wrong.
I think that if they value money over anything else, it makes them greedy. You don't. Neither is wrong or right, it's just opinion.
Quit trying to fill your ego by winning debates that are really undebatable. There are no facts that we can use to support either side, it's all opinion. So what's there to debate? Nothing
You are right in saying that your opinion in this instance can't really be "wrong," but that isn't to say that one's opinion cannot be superior to another opinion. How we value a given opinion is based on the quality of argument that presents that opinion. If one supports their argument using facts and evidence and another has no such support, it usually indicates that the first argument is superior to the second. Clearly, in this particular situation, there are no real forms of evidence or facts that can be provided which prove one's argument. That does not mean we cannot determine which argument/opinion is superior. By looking at the rationality or logic behind one's argument/opinion, we (the public) can determine which argument is superior.
The thing about an opinion is that it is entirely meaningless within the individual and only establishes its value when it is presented within the public sphere. Once an opinion/argument is presented to the public, the public (in this case being the forum members) can then determine the validity of that opinion/argument.
Now in regards to your original question concerning whether or not athletes are overpaid and greedy, my response would be that we all live within a global liberal order and this order essentially forces those within it to adhere to a world where monetary gain rules all. It doesn't matter if you're a secondary school teacher, doctor, professional athlete, businessman, university professor, lawyer, veterinarian, or a wannabe communist reading some Karl Marx off of a MacBook while sipping on a Starbucks coffee, the almighty dollar rules over you as it defines your interests. Nothing can be accomplished in the modern world without monetary involvement. If your interest is helping starving children in African, you cannot, in any way, fulfill your interest without a source of money.
As one begins to accumulate more money, their interests begin to change and expand. The working-class man may not be interested in the $10 million mansion, but that is because his money situation does not allow for the $10 million mansion to be a conceivable interest. In other words, money, or rather a lack thereof, makes that reality so distanced from the working-class man that it has no real impact on his interests. Give the working-class man $100 million and 99 times out of a hundred his interests will be entirely reshaped by that monetary transformation. For this reason, it becomes very difficult to scrutinize professional athletes for their apparent "greed" and "selfishness" in regards to money as we (the general public) have, in most cases, not been provided with the possibility of garnering immense wealth and, therefore, we do not have the perspective that would grant us the ability to understand the situation.
I feel that the real target of your opinion/argument is the liberal economic order itself; an order which forces its subjects to adhere to a world of monetary rule. It is of my opinion that it is within the nature of people to act in their own best-interest and, as money currently rules over everyone's interests, it is thus acceptable on a human level that people will strive for as much monetary gain as possible.