From the Dark
Many elves view themselves are caretakers of the world. Their long lives mean they see rising evil as it happens and many times also see its downfall. Some elves of the past viewed the shorter-lived mortals almost as children.
This all changed with the curse. The elves didn’t foresee it. And once it was there, their failed attempts to stall it led to the creation of the drow. No elves live that remember life before the curse. They are now humbled and live in the same fear of the inevitable that the rest of the world does.
Elves of today are scattered around. The nation of Galaana is the elven nation. Few non-elves live there. But many elves live elsewhere. They can take on any role and have a variety of motivations. Those that enter the mists could go for any number of reasons, but a common reason is a desire to once again protect the world.