First of all, you reached an oral agreement (evidenced by the chat record), which is protected by the contract law. You fulfilled the agreement, but he didn't pay. He has violated his contractual obligations, and should bear the liability for breach of contract and compensate for the losses. But this is a civil liability, which does not constitute a criminal offence. It is useless to call the police.
Second, you can sue. But do you know the cost of litigation? Win or lose, can you spend time and energy on this 1000 yuan? Can his people find it? A lawyer? All the evidence? How much is it to consult a lawyer? Wait, wait, wait.
So several people upstairs are right, LZ can only condemn him with moral power. I study law myself, but the law is not omnipotent and the feasibility cannot be comprehensive. I hope that this phenomenon will be put an end to after the legal system is perfected.