The text can be changed but people make screenshots all the time and itch has probably versions saved including IP addresses.
ChatGPT says: Even if the competition is private, failing to deliver on a promised monetary prize could still be considered a breach of contract or fraud, depending on the specific circumstances. If the amount of the prize is relatively small, you may be able to file a lawsuit in small claims court. This is a less formal court process that can be more affordable and quicker than a traditional lawsuit.