Most watched video on youtube ever. He's 8 million dollars richer since "Gangnam Style" blew up.

But when people learned of his 2004 rap in which he said:
Kill those f***ing Yankees who have been torturing Iraqi captives; Kill those f***king Yankees who ordered them to torture; Kill their daughters, mothers, daughters-in-law and fathers; Kill them all slowly and painfully.

This was after a Korean missionary was killed by the Taliban who said it was in response to the US invasion of Iraq. Not long before that, an American military vehicle struck and killed two Korean children in a terrible accident.  Anti-American sentiment in Korea (still protected by American soldiers from North Korea) was riding high.

Psy's apology:

As a proud South Korean who was educated in the United States and lived there for a very significant part of my life, I understand the sacrifices American servicemen and women have made to protect freedom and democracy in my country and around the world. The song I featured on in question from eight years ago—was part of a deeply emotional reaction to the war in Iraq and the killing of two Korean schoolgirls that was part of the overall antiwar sentiment shared by others around the world at that time. While I'm grateful for the freedom to express one's self, I've learned there are limits to what language is appropriate and I'm deeply sorry for how these lyrics could be interpreted. I will forever be sorry for any pain I have caused by those words.

I have been honored to perform in front of American soldiers in recent months—including an appearance on the Jay Leno show specifically for them—and I hope they and all Americans can accept my apology. While it's important that we express our opinions, I deeply regret the inflammatory and inappropriate language I used to do so. In my music, I try to give people a release, a reason to smile. I have learned that thru music, our universal language we can all come together as a culture of humanity and I hope that you will accept my apology.

 President Obama has been criticized for attending a TNT tv special that featured PSY's performance. When he spoke during the special, he didn't address the PSY controversy.  People petitioned the official White House petition page, but it was removed from the White House site because "It violated the terms of use".  But they didn't say how.