Several famous people often wanted to be somethimng very different from what the achieved fame for. Sometimes it is or was something that would be surprising.
examples are; Radovan Karadzic had a spell where he wanted to be an enviromentalist. Hitler; famously an artist.
Can you think of any. It must have been something seriously contemplated not just a passing fancy. And it must be sufficiently different that you would never associate the two.
Dick Van Dyke’s hobby is 3D computer animation. He sees an effect sequence in a film and tried to duplicate it.
Peter Weller teaches literature and fine arts classes at Syracuse University. He holds a master’s degree in Roman and Renaissance art and is working toward a Ph.D. In an interview, he says a lot of students think they’ll get an easy “A” from “Professor Robocop”, and he gets a lot dropping his class in the first week.
Brian May lead guitarist of Queen holds a PHD in…astrophysics! He has published two articles.
John Travolta seriously considered becoming a commercial airline pilot when his career was on the wane (pre-Pulp Fiction). He loves flying, he named his (recently deceased) son Jet.
Fidel Castro wanted to be a professional baseball player.
Stricken! Misread OP.
John Malkovich is a master puppeteer.
Actors want to be rock stars. Rock stars want to be race car drivers. Race car drivers want to be pilots.
Pilots always want to fly bigger, faster planes.
Mickey Rourke was one of the biggest leading men of the 80’s, but gave it up to be a professional boxer. He had a 6-0-2 record with 4 knockouts.
He went to my undergrad. 
Daniel Day Lewis makes shoes.
Geena Davis is an accomplished archer and made it to the finals for America’s Olympic team.
Ed O’Niell (Al Bundy) is a Brazilian Jiu-Jitsu black belt under Rorion Gracie.
Heath Ledger was a talented chess player; some friends claim (or perhaps exaggerate) that he intended to pursue the rank of grandmaster some day.
Reinhard Heydrich and Iron Maiden’s Bruce Dickenson are/were both Olympic class fencers.
John Malkovich or “John Malkovich”?
So was General Patton, he placed fifth in the Modern Pentathlon at the 1912 Olympics.
Dexter Holland from the Offspring was working on his PhD in molecular biology from USC, but quit to focus on the band. He managed to at least get a masters, though.
Not realistic, I know, but Joan Jett would have sacrificed it all to be the starting center fielder for the Baltimore Orioles.
There’s no evidence that Fidel Castro seriously wanted to be a professional baseball player.
Similarly, Greg Graffin of Bad Religion has a PhD in zoology, and teaches at UCLA.
Tammy Wynette famously maintained her cosmetology license throughout her musical career. Lyle Lovett was a journalist before he was a professional musician. Sting and Gene Simmons were both teachers.