Christians have a lot of rights. True Christians do not have to earn their salvation by taking vows of poverty or living a strictly ascetic lifestyle. We have the right to make a decent wage, eat good food, and live in comfortable houses. Even God’s ministers have these rights. Nevertheless, sometimes we ought to give up these rights in order to serve the higher cause of spreading the gospel message. Sometimes we need to give up our comforts in order to prove to unbelievers that we are more concerned about their salvation, than we are about making money. This is why the Apostle Paul Himself refused to accept donations from the new churches that he was founding:
Nevertheless, we have not made use of this right, but we endure anything rather than put an obstacle in the way of the gospel of Christ. (I Corinthians 9:12 NIV)
What Paul is saying here, is that missionaries like himself have a right to be financially supported by the churches that he was founding. Nevertheless, he forwent that right, and supported himself with his hands, so that these young churches could know that he was not in the missionary business for personal gain. This would make it easier to trust him. If he had chosen to exercise his right to beg paid, he might have ended up putting an obstacle in the way of the gospel of Christ.