O'Brien was born on April 18, 1963 in Brookline, Massachusetts. His father, Thomas Francis O'Brien, is a physician, epidemiologist, and professor of medicine at Harvard Medical School. His mother, Ruth O'Brien (nee Reardon), is a retired attorney and former partner at the Boston firm Ropes & Gray. O'Brien attended Brookline High School, where he served as the managing editor of the school newspaper, The Sagamore.

On Thursday, January 7, 2010, NBC executive Jeff Zucker met with Jay Leno and Conan O'Brien to discuss how to get Leno out of prime time, where his ratings were lackluster, and back into late night, where O'Brien's ratings had collapsed before Leno's prime time series began. A proposal was made that would see O'Brien remain as host of The Tonight Show, which would be moved to 12:05 am with Leno hosting a 30-minute show at 11:35 pm On January 10, NBC Universal Television Entertainment chairman Jeff Gaspin confirmed that The Jay Leno Show would indeed end at the start of the Winter Olympics on February 12, 2010, and be moved to 11:35 pm following the Olympics coverage. Sources familiar with the situation told the New York Post that O'Brien was unhappy with NBC's plan. On January 12, O'Brien released this statement: "I sincerely believe that delaying The Tonight Show into the next day to accommodate another comedy program will seriously damage what I consider to be the greatest franchise in the history of broadcasting. The Tonight Show at 12:05 simply isn't The Tonight Show." On January 21, 2010, it was announced that Conan had reached a deal with NBC that would see him exit The Tonight Show the next day. The deal also granted him $45 million, of which $12 million was designated for distribution to his staff, who had moved with Conan to Los Angeles from New York when he left Late Night. The final Tonight Show with Conan aired January 22, 2010, and featured guests Tom Hanks, Steve Carell (who did an exit interview and shredded Conan's ID badge), Neil Young (singing "Long May You Run"), and Will Ferrell. For Ferrell's appearance, Conan played guitar with the band and Ferrell sang "Free Bird" while reprising his SNL cowbell. Ferrell's wife, Viveca Paulin, together with Ben Harper, Beck, and ZZ Top guitarist Billy Gibbons, also joined the band for this final performance. Jay Leno returned to The Tonight Show following NBC's coverage of the 2010 Winter Olympic Games. Under the $45 million deal with NBC, Conan was allowed to start working for another network as soon as September 2010. Conan's rumored next networks ranged anywhere from Fox to Comedy Central.

Answer the following question by taking a quote from the article: Why did he leave the show?
O'Brien's ratings had collapsed