that doesn’t really make any sense. Thais have citizenship at birth, not after a lifetime. If someone is living and working here and wants citizenship, and if they’re younger, we can assume they will keep working and contributing for a long time.
I was with you up until you started talking about canceling an extension before leaving. I’ve never heard of that, never done it and never had any problems.
Normally, you need to come in on a 60 day tourist visa and then convert it to a Non O. After that you apply for the extension based on retirement. There is no such thing as a “retirement visa” as some here have used that term.