A buddy of mine is a hardcore rider. He goes through a $5k bike every 5 years or so.
Could he refurb the titanium frames for newer parts? Maybe. At some point racing tech moves on and you need a newer frame for the latest and greatest stuff to fit.
Your friend just want a new bike every few years, he doesn't go through it. I have been in that place. That doesn't mean older stuff becomes unrideable and unfixable.
You can find parts for nearly any kind of old/obsolete bike technology ever made in volume, even tires for odd wheel sizes that have been mostly abandonned can still be found.
Nothing gets consumed, he just gets bored with his 5 year old bike and wants something that has all the latest new tech. He probably got a new 12-speed bike in the last year just because it's 1 more speed than the older 11-speed bikes from 5 years ago, for instance.
Could he refurb the titanium frames for newer parts? Maybe. At some point racing tech moves on and you need a newer frame for the latest and greatest stuff to fit.