This is just plain weird to us. It's a standing joke in Hollywood that Nicolas Cage will never turn down a movie role. His love of spending money is legendary, and so he needs to make big money so he can carry on spending it. That's why for every great Nicolas Cage movie you can think of, there are two or three terrible ones. So long as the money is right, you can count on Cage signing a contract and doing the job.
Maybe the money on offer wasn't right when Peter Jackson asked him about playing a role in the 'Lord of the Rings' trilogy. It was the 'Fellowship of the Ring' film that would have made use of Cage's services, and he'd have been playing Aragorn. Cage spoke to Jackson and apparently considered the offer, but said no. Once the director and his team had recovered from the shock, they persuaded Viggo Mortensen to play the part instead.