To have the woman you loved taken away to be a corporate honcho’s whore and then returned as a “retirement” inducement?
What an a$$hole.
The game taking place of war for control of world regions/economies would make for a better backstory.
It would be bloodier and have NO rules.
If you read the original short story, Rollerball Murder, it is even more gory than the film. There are oblong balls that are harder to handle, tear away jersey to expose the male and female skaters to make them more vulnerable. Jonathon knows they will keep on changing the rules until they "skate on a slick of blood".
Despite this, Jonathon loves the game. He lives better than some executives, Bartholomew is a friend and mentor. He wants more power.