For Your Anticipation: Doing All the Extra Work

Can somebody explain to me how Kevin Spacey ended up working on a film like Horrible Bosses? I understand Jason Bateman, Jason Sudeikis, Jennifer Aniston, and even Colin Farrell, but you can tell that Spacey is the main antagonist. Apparently Tom Cruise, Phillip Seymour Hoffman, and Jeff Bridges were all considered for the role, and while I feel like Cruise may have been a better fit, I'm glad they chose Spacey. I understand that none of this weighs on the quality of the film, but I really couldn't care that much. I suppose it could've been a lot worse, but it's still just lower tier fare.