He did say why around the time Ghost Rider came out.

“Actor Nicholas Cage has revealed he gave up his love of comic books after part of his beloved collection was stolen. The star, who appears in new comic adaptation Ghost Rider, was so upset when his favourite graphic novels were stolen that he decided not to pursue his hobby any longer. “Three of my best comics were robbed – Action One, Detective 27 and Detective 14,” says the Con Air star. “Those books today would be worth, I don’t know how much, more than the whole collection itself was at the time. It occurred to me that I didn’t want that in my house anymore because I didn’t want that sort of temptation for people to do that, so I sold everything.”"