Tourbillons were desgined to help overcome the forces of gravity. Breguet was messing about with them in the late 1700’s. The idea was to improve positional errors and improve the overall time keeping which, they can do, but, as David rightly points out, most are just there to show what some of our watchmakers are capable of, I also would hate to think how much it cost to have one of these watches serviced but then if you can afford to buy one in the first place I doubt it is an issue. I think they are beautiful pieces of engineering and only wish I had the skill to make one, who knows, maybe one day 
