Let me point out something that has seemed to slip by most of the Lost fans out there. This is in regards to some very important plot points that basically started the entire premise of the show. Here it goes, stop me if I'm wrong.
Jacob created the Smoke Monster by throwing him into the golden cave. His body died, but his 'soul' became the Monster. This said Monster would destroy the world if he ever escaped the island, so to protect the island and keep him there, Jacob became the protector, the next Candidate. The Smoke Monster cannot kill Jacob because of the rule their fake-mother put into play; Jacob is also immortal because of drinking some weird wine shit. Whatever, I won't question the mundane details. Here's the real problem with all this.
Jacob can't die from old age, he can't die by the Smoke Monster's hand. He can only die when the Smoke Monster finds his loophole, which takes the form of Ben Linus. Ben was one of the many people brought to the island by Jacob himself. Why? Because Jacob needed to find a replacement... but DID he? In what other way could the Smoke Monster have killed Jacob if no one else ever came to the island? What if, instead of spending all his time drawing innocent people into his dumb mistake, Jacob kept them AWAY from the island?
My point is, the entire plot of Lost is a glaring hole due to this giant mistake. Jacob brought people to the island who could kill him, believe in the Smoke Monster, and help him off the island, when all he had to do was sit there and live with the Monster he created. Epic fail.