I wanted to do this so bad back in like 2009. I archived MSN messenger chats and my texts and everything and I figured sometime in the future I'd be able to analyze them and maybe even train a chat bot to imitate me. But over the years I lost hard drives and cell phones and accidentally deleted stuff and yeah it didn't happen. Very cool this guy was able to do it
I logged with AIM which was a pain, at least for the late 90s version I was using, bc you had to save each chat manually. Then a Kramer-like friend wandered over when I wasn't home, got on my computer, came across the saved chats, and deleted them all. I did this kind of self-logging for the same sort of navel-gazing reasons as the OP but it really turned off friends, who thought it was about keeping a file on them.
I have my msn logs along with a lot of old stuff in an ecrypted hard drive with a password I have forgotten. I am waiting for divine enlightment to remember the password, or quantum computers to finally come.
Weirdly glad to hear I am not the only one effectively having lost them.
I used to have saving turned on for my MSN Messenger chats back around 2001-2004. I didn't lose them. 10-15 years later or so I had a look through them and the cringe was so powerful that I deleted them all anyway.