Speaking with Flare in 2020, Paris even admitted she'd rewatched every single season.
"It makes me feel so happy because I feel like that show [was] the first of its kind and so original," she said.
"I love that people dress up as Nicole and I for Halloween; and now that [the show’s] streaming, people can easily enjoy it. It just makes me so proud."
Though they're no longer best friends, Paris confirmed in 2019 that she and Nicole still speak.
WATCH BELOW: Paris Hilton reveals if she still talks to Nicole Richie. Post continues after video...
So where are the show's two main stars today?
Paris, 40, has an estimated net worth of US$300 million thanks to her various retail businesses.
The hotel heiress' career has seen her star in movies, produce her own music, DJ and she now has her own show on Netflix, Cooking with Paris.
On a personal note, Paris announced her engagement to businessman Carter Reum in February 2021.
Nicole, meanwhile, has had various TV ventures since her days on The Simple Life, from reality shows Fashion Star and Making the Cut through to her role as Portia Scott-Griffith in sitcom Great News.
However, it was fashion where Nicole found her true calling and has her own label, House of Harlow.
In December 2006, the Simple Life star started dating musician Joel Madden who she married in 2010. The couple share daughter Harlow, who was born in January 2008 and son Sparrow, born in September 2009.