how do the wise become wise

Wisdom is gained only through experience and reflection upon that experience. The ability to see the big picture as well as patience are what make a person wise. I guess the elves and wizards are wise because they have had time to see many things and how they change over time. They understand why things are the way they are because they saw how they started way back when. They've seen how things happened in the past so they can more easily see where things are leading in the present.