As someone who actually deals with this on a regular basis, I can guarantee you that serious companies definitely do not "just put everything in ChatGPT" if they have any sort of respectable legal department. Especially in Europe, where you have GDPR concerns on top of any business concerns. People who actually understand the privacy issues nowadays either use stuff like Azure's OpenAI custom hosting to be compliant with the law or go full open weight self hosted. Everything else is a legal time-bomb.
Of course they aren't putting it on ChatGPT. Their data is stored in S3, Snowflake, BigQuery, or Azure Storage. It makes more sense to use the respective cloud provider LLM hosting service. You can use OpenAI's GPT models or Anthopic models hosted on Azure or AWS.
You're telling me companies in Europe aren't putting all their user data on AWS and Azure regions in Europe? Both AWS and Azure are gigantic in Europe.