Unfortunately, this is not an ungrounded fear. There have already been instances of clone websites setup that mirror other sites content, feed those blog posts through GPT and rewrite them, passing them off as their own. There was a link pasted to HN not too long ago about this very issue.
TLDR: Feeding your own ideas/thoughts into GPT to rephrase them in a logical, consistent and more fluid manner is a great use of the tool. Using it to plagiarize other's ideas without citing your sources shows a staggering lack of integrity.
https://slate.com/technology/2023/01/chat-gpt-openai-jasper-...
TLDR: Feeding your own ideas/thoughts into GPT to rephrase them in a logical, consistent and more fluid manner is a great use of the tool. Using it to plagiarize other's ideas without citing your sources shows a staggering lack of integrity.