Warner Bros. Pictures has been trying to get a sequel/prequel/reboot going for I Am Legend ever since the 2007 movie made $586 million worldwide, but the studio has failed to come up with a satisfactory script or lure Will Smith back to the project (spoiler: yes, he died in the first film, but the studio was toying with the idea of a prequel for a while).
Enter Gary Graham, who was working as a sales clerk at the Apple Store in midtown Manhattan when he posted his original screenplay, called A Garden at the End of the World, to the Black List, a website where aspiring screenwriters can post their scripts and possibly have them seen by producers, filmmakers and studio execs.
Someone at Warner Bros. liked Graham's screenplay and bought it last April, but then the studio noticed that there were enough similarities to the basic I Am Legend concept that when they brought Graham in to discuss rewriting his screenplay, they asked him if instead he'd be interested in adapting it into the I Am Legend mythology.
Graham said yes (wouldn't you?) and has been busily reworking his script, although at this point it still will not involve Smith. Graham's original tale was said to be a a sci-fi version of the classic John Wayne western The Searchers, but it's not known whether that will morph into a prequel, sequel or straight-up relaunch (by the way, this is hardly the first time this has been done; for example, an original script called Simon Says was mutated into Die Hard With a Vengeance).
And yes, Graham did quit his job at Apple and is now making his living as a screenwriter. So what are you waiting for? Day job or not, if you make the effort your script can also attract the attention of Hollywood. It may turn into something completely different from what you started out with, but hey -- at least you'll get your foot in the door.