"The crown" is a symbol of the completion, the consequence of spiritual or physical efforts, the aspirations to which the purpose and meaning of one's life was devoted.
"The Crown" is the symbol of victory over sin, the symbol of the glory of man crowning his pious life, in doing the Will of God, in following His Commandments. 
It is a symbol of Eternal Life crowning a man who lives in righteousness. The result, the consequence of a person's good deeds.
The "crown" of thorns is also a symbol of the moral and physical suffering of Jesus Christ and all the innocent righteous, who throughout history were persecuted and killed for their proclamation of the Truth of the Word of Holy Scripture, for exposing the evil, the lie, created by the lawless.