tl;dr sheridan pitched it to him as a 1 season movie essentially and costner loved everything about it. then the network was like heres all the money in the world so sheridan said ok ill make it 3 seasons and costner said uhhh i guess? and then it dragged out to 5 seasons. and now theres still no script for season 5b or whatever the fuck and costner really doesnt want this show to be his whole world, he has things he wants to accomplish, so its impossible to stay attached.

which is super, super reasonable.

so the western trilogy that costner was so obsessed with making his whole life that he dipped on the final season of this soap opera had bombed so hard financially that the studio has written off the second installment from theater release already.