This was recently posted in another thread, and is a great explanation IMHO…
excerpt:
Note that He is talking about the “poor in spirit” here. In other words, those who are aware of their own smallness and emptiness. The poor in spirit are not those who beat themselves up, but those who frankly recognize how puny they are before the mysteries of the universe and the Creator of that universe. They don’t let their own accomplishments and abilities blind them to their mortality and vulnerability. They don’t fool themselves.
Jesus mentions elsewhere how hard it is for the rich to enter the kingdom because it is very easy for the successful to lose touch with their neediness and to actually believe the flattery of the fan club. Those who are not influential, educated, or wealthy have an easier time recognizing their need since it stares them in the face every place they turn. For this reason, the Church was full of such people in the New Testament era (1 Cor 1:26-31) just as it is today.
The poor of spirit are empty and so long to be filled. They hunger and thirst for the wholeness that is called holiness, for the food that truly satisfies.
The rich in spirit don’t hunger for anything. They are “full of themselves,” self-satisfied. When offered an opportunity to grow spiritually, they protest, “But I’m a good person and worship God in my own way,” or “I go to Mass every Sunday, isn’t that enough?” They are too busy for prayer and yawn when exposed to a spiritual discussion. They are too absorbed with themselves to be interested in God. They may be able to get excited about the Superbowl, but never about heaven.