Karl Lagerfeld was once
link asked in
link an issue of Architectural Digest whether he was particularly obsessed with any design objects. His answer as translated in this 2019 thread on WatchProSite cited the Royal Oak as a "fetish object" for him and the watch he's "worn for 35 years." For what it's worth it appears the watch highlighted
link in the WatchProSite thread linked above is identical to the one Phillips is auctioning off they have identical bracelet numbers.