There is no doubt that millions of dollars annually is a huge salary, but it may be less than the income of many businesspeople and owners of companies with multimillion-dollar profits. The issue here is not about the sum of money received, but rather about the way of earning it. If a given income is the outcome of legal acts, it will be legal even if it reaches millions of dollars.
We believe that if the work done by players in permissible kinds of sports has nothing to do with any prohibited acts, it is permissible. Consequently, its income is legal regardless of the sum.
Muslim athletes are legally obligated to pay zakah, and if they have such large salaries, they are recommended to give more in charity, especially to the poor near them.
The same applies also to teams that earn large profits. It is desirable for them to allocate part of their income to help the poor.