As an example of limiting your rights for the sake of someone else, Paul expounds his rights as an apostle that he declines to exercise. He made very deliberate, costly and personal choices so he could be sure to make the gospel the issue. He didn't want his personal freedom to be the cause of someone dismissing the gospel.
To the Jew he became a Jews . . . to win more. He limited his freedom with certain people -- that's his argument. He did not add to his freedom to win them, I don't think. Many use this in the opposite direction, "to the cool, I became cool (doing things I've always wanted to do), to win more cool people." That is not his point at all.
I love the focus of 1 Cor. 9:24-27. It forces me, each time I read it, to re-examine my own focus.