He opted out of his contract. He made his own bed...
Not many NFL contracts are guaranteed beyond signing bonuses. One of the few smart things CK did was to opt out early rather than have the team cut him just before the season when teams would already have their rosters set.
His contract was for $14.5 million this year, which the ‘49ers couldn’t afford for a part-time player. Unlike MLB and the NBA, NFL teams don’t have to cough up the money for bad decisions.