That Paul preaches the gospel free of charge
is only one part of his selfless, gospel-centred lifestyle. In 1 Corinthians 9:19–23, he will give a broad summary of this lifestyle. He begins this summary by again reminding the Corinthians that he is a free man (compare 1 Corinthians 9:1).
Paul, a free man, has made himself a “servant [or slave
] to all.” He has done this in order to win for Christ as many people as possible.
19 For though I am free from all, I have made myself a servant to all, that I might win more of them.