80 or 90 thousand would of course be the EXTREME case(s).
But by all accounts it's what guys like Coltrane, Dolphy, Beethoven did do. They 'worked' 8 to 13 hour days regularly for many years.
Most folks back it off after they've made it but successful musicians continue their entire career to practice/play/gig/rehearse at least three hours a day. Nine years of that and you've got another 10,000 hours. Most pros have least 30 years of a career. The average good, professional player - by age 60 has probably 40 to 50 thousand hours in.
The handful of extraordinary, super human, seemingly unearthly talents I'm convinced put in closer to the 80 to 90 thou. *It is well doc'd that Trane and Dolphy did in fact play all day, everyday (after school, weekends, holidays and summers ) from a young age and into their professional careers. Coltrane was known to not take breaks on rec sessions instead opting to work on something else. Beethoven was an insomniac/workaholic. Ellington - wrote out parts while riding the train. So many musicians over-book themselves and they CAN'T not work all day or they won't meet the deadlines (Bach and Mozart come to mind). These guys NEVER stopped. Their contribution not just to the art but society and culture is a testament to that drive.
This is why I always maintain that the 'genius' (or the talent gene) that they possess is in the drive and desire.