The first beatitude Jesus taught introduces us to one of the great paradoxes of the Christian faith: the truly rich person is the one who is poor in spirit. Listen to that carefully. Poor in spirit. Jesus was talking about things spiritual not material. Yes, the beginning of happiness is the admission of spiritual poverty.
The person who is poor in spirit accepts God's diagnosis of his spiritual condition. Picture a beggar who is totally broke, spiritually bankrupt, and humble enough to admit it. Absent is the kind of arrogance and pride that says, "I'm okay, you're okay!"
The kingdom of heaven welcomes the poor in spirit, and considers them one of its wealthiest citizens.