When an offer given is not accepted, it's an insult to the host. More evenly, when a King's invitation is rejected, the King himself feels that it's not the invitation which they rejected, but himself. That's the reson why the king was so angry when those invited did not come to the wedding banquet. Moreso, some of the invited  guests "grabbed his servants, treated them shamefully and killed them". Then, who is that King who will not be angry with these?

What Jesus wants to drive home  when He said this parable was to open up the spiritual eyes of those who believe in the "King son's marriage feast". Jesus is the Father's beloved Son. The Almighty Father has spent His time preparing  for His Son's marriage. We, Christians are the bride, (if not the invited guests). Jesus is the groom. If we don't give honor (accept) to the invitation (of Salvation), we will find ourselves "thrown in the darkness, where there is endless weeping and gnashing of teeth".