"Wisdom" means "that which is pounded in". Wisdom is learned when we let life pound its lessons into us. Unfortunately sometimes we would rather not learn. We are too proud, too scared, or too distracted to listen and learn from our life experiences. Taking the time to work through our past and ask what we can learn from it is one of the hallmarks of true wisdom.
"Wise people get wiser. Foolish people get foolisher." P. Diddy