This is true but you can AI knowledge with private data. So if you are able to capture the interactions in a meaningful but static way you may be able to avoid some of the issues you are having.
It does come at an increased cost depending on how much data you need to capture to make this work. You would also need an upscale account with your favorite AI vendor.
Medium has a bunch of articles on how to customize ChatGPT with private data.
The ChatGPT store has some private/new data models constructed by individuals that you can use. You can even create your own though I haven't delved into the details. The ones I have looked at in the ChatGPT store are essentially black boxes and I don't see any information as to how they were trained on specialized data.
I am a ChatGPT plus subscriber.
The problem I mention is not so much one of data as it is one of getting an AI platform to adapt to me (to recognize me and record what we have learned together as part of its training).
This is most notable when I have spent a great deal of time working with ChatGPT on a project. From one day to the next, it forgets what it might have learned from the prior day. It has a record of our prior discussions but what is learned (concepts and principles) from those discussions doesn't get included in its knowledge base.
I will check out the ChatGPT store.;-)