I just always assume that elves are just really big slackers. Until they get the call to go adventuring, they usually just hang out around home, admiring daisies and chasing butterflies and the like. They learn just as fast as humans, but for their first century, they just don't bother to learn much.
I'm reminded of an elf's insult of humanity: "Every day the same, every decade different." Sure, that doesn't sound like an insult to humans, but the translation is basically: Humans live a life where they are trapped into the same short series of actions. However, in the long run, their lives are highly unstable. Elves prefer to live a life in which you can do whatever you feel like each day. The lack of ambition, and subsequent lack of honing your skills, gives you a life that is far more stable. The human sees this as both a lack of advancement and destruction of opportunity, though, which is why the insult means very little to humans. A human homebuilder may spend every day building homes, but over time, he builds a city. An elf homebuilder might spend only one day out of ten actually building homes, the rest spent visiting family, making sure the trees grow just right for the perfect grain, agonizing over the color of the paint, following that squirrel he happens to like, etc.
The elf has the luxury of processing the world at a slower rate. The events of the day may change, but the decades are the same. They do not dream because they do not see the world as humans need to. Bursts of insight, great conviction, dangerous ideas--these are all characteristics (flaws?) of humanity. An elf would never attempt such brazen and unproven tactics. You build a city, but what of the forest?
