Wisdom comes from experience
- ie. making mistakes and is part of the learning process.
Smart people sometimes get into the habit of thinking they know everything and hence the ability to learn is limited.
People who think a lot about things that happen to them and learn how to analyse and learn from them develop this wisdom.
I also feel that age has something to do with it. Dr. Scott Peck described the levels of psychological maturity
. Some people remain at the same level and don't progress.