The king was angry because He was some how ridiculed.He could not imagine how one would prepare very well for a banquate and is begging people to come and eat without any payment and they refuse.They did not only refused but molested His servants and killed them.

Jesus is insinuating the wayward nature of human beings.Whereby everything has beenn taught but yet some were still doubting Him.Even when He said if you do not beleive in me beleive at least the things that are do like healing of the sick,casting out demons etc.It is rediculous that even those who were following Him were just a multitude.So He decided to let them know that only few people will be called in Heaven and the rest will perish in hell.