How do the vintage road bicycles compare to the new carbon fiber bikes in quality of longevity.?

I have vintage road bike that is 34 years old and is still as strong as it was new. I weigh over 230 pounds and 6'2". I'm not sure how close to the original price is of my Koga Miyata Road Winner new but I'm guessing around $600 34 years ago and at least a $1000 for a carbon with a cheap group.
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