Part of 2 Corinthians is a defense that Paul makes about his ministry and actions, including a discussion on the church giving financial aid to those in need.
Paul wants them to be cheerful givers and does not want to use his authority to coerce them. Instead he tells them about what Christ has done for us.
2 Corinthians 8:9
For you know the grace of our Lord Jesus Christ, that though he was rich, yet for your sake he became poor, so that you by his poverty might become rich.
Rather than command the church in Corinth, he tells the gospel again in the language of money. If they understand the gospel and accept it, Paul believes they will act according to it. He writes in chapter nine about a “submission that comes from your confession of the gospel of Christ.”
Tim Keller in Counterfeit Gods describes 2 Corinthians 8:9 like this:
Jesus, the God-Man, had infinite wealth, but if he had held on to it, we would have died in our spiritual poverty. That was the choice–if he stayed rich, we would die poor. If he died poor, we could become rich. Our sins would be forgiven, and we would be admitted into the family of God. Paul was not giving this church a mere ethical precept, exhorting them to stop loving money so much and become more generous. Rather, he recapitulated the gospel. (Keller, Counterfeit Gods, 67)