Amos Preached Destruction of the Wicked

Today I read Amos 1 where the Lord talks about the things He will do to the enemies of Israel.  I wonder if the people of Israel need constant reminders and that is why so many of the prophets focus on these things.  I understand that the prophets just tell the people what the Lord tells them to say, but it just makes me wonder why the Lord keeps reminding His people that He will punish the wicked?  You would think that the righteous would get the message and do what is right no matter what.  And the wicked?  Well I guess it would be very interesting to see the numbers surrounding what percentage of people actually repent after being told that they will be punished over and over again.  We know the Lord never does anything without a reason, so we can at least be assured that there is a purpose behind it.  We just need to find it so we can apply it to our own lives.  Until tomorrow.