What is their crime?

 Then another came, saying, ‘Lord, here is your mina, which I kept laid away in a handkerchief; for I was afraid of you, because you are a severe man. You take what you did not deposit, and reap what you did not sow.’ He said to him, ‘I will condemn you with your own words, you wicked servant! You knew that I was a severe man, taking what I did not deposit and reaping what I did not sow? Why then did you not put my money in the bank, and at my coming I might have collected it with interest?’ And he said to those who stood by, ‘Take the mina from him, and give it to the one who has the ten minas.’ And they said to him, ‘Lord, he has ten minas!’ ‘I tell you that to everyone who has, more will be given, but from the one who has not, even what he has will be taken away. But as for these enemies of mine, who did not want me to reign over them, bring them here and slaughter them before me.’” (Luke 19:20-27 ESV)
To the casual observers whom the new King commanded to take away the mina from the disobedient servant, it seemed like the punishment was excessive what had he done? He claimed to know the King, when he really did not; he did not obey the command of the king to invest what he had been given - he did not even put it in safe place. He had total disregard for the King, His word, His treasure, and His plan.  Thus the even harsher punishment on those who opposed the King's reign. You cannot ignore an outright rebellion.  Would we expect anything less of a challenge on the last leg of the journey to Jerusalem?