Many people now use ChatGPT like they might use Google: to ask important questions, sort through issues, and so on. Often, sensitive personal data could be shared in those conversations.
Don't a lot of people also keep their tax information as plain text in their PC? If someone's really worried about that stuff being leaked I think it's on them to download VeraCrypt or smth, and also not to use ChatGPT for sensitive stuff knowing that OpenAI and Apple will obviously use it as training data.