Blessed are the Poor in Spirit

Christ is the lord of lords and the king of kings.  He is God who has taken on the flesh to save his people from their sins.  If Christ is a king you would think that his priority would be the successful rain makers of this age who make things happen.  It would seem that Christ desires to save those worthy of his time.  However, Christ says blessed are the poor in spirit?  What does it mean that the poor in spirit are blessed?  How does such a blessing communicate Christ’s mission?