ON'T lose sight of the context of 1st Corinthians 9. Paul has been talking about Christian liberty, and about how we should voluntarily (vs. 17) use our freedom to pursue personal holiness and to promote cordial fellowship among believers. Our freedom was not given to us for the exploitation of others. So, we are free, but how should we live our lives now that we are unrestricted? Paul points to diligence, self-sacrifice, self-discipline, and faithfulness (vs. 19).
The great apostle set an exemplary standard for all of us with his own habits. He was good at living his message. As an apostle and a preacher of the gospel of Jesus Christ, he had every right to accept remuneration for his ministry to the churches (vs. 6, 11 & 14). This was the law and principle of both the Old and New Testament. However, understanding his freedom from the law and the spirit of that principle, Paul required more of himself than the written law required (vs. 18). He worked a secular job (earning his own money without accepting a salary from the churches in which he served). Apparently other apostles accepted finances from the church. There would have been nothing wrong with Paul doing the same. But, he didn't. By trade, he was a tentmaker (vs. 6). He lived simply and worked with his hands to supply for his own needs. To what end did Paul choose this hardship? He realized that if he refused gifts from his converts, then nobody could question his motives. The propagation of the gospel is worth that burden (vs. 12, 15 & 19). For Christ, he was willing to give up anything (vs. 27).