'I moved to Germany when I was young, and went through so many really difficult, unimaginable moments,' said Son, who left Hamburg in 2013 for Bayer Leverkusen.
'I faced a lot of racism. And while going through such a really difficult time, I had a lot of thoughts on my mind I should get my revenge one day.'
Germany were the defending World Cup champions in Russia but the shock defeat to South Korea meant they finished bottom of their group, leaving many German fans in tears at the Kazan Arena.
Son, who scored the second goal in injury time to seal Germany's early exit, said he had little sympathy.
'When people cry, I'd (usually) want to comfort them and give them a hug,' he said.
'But watching German people cry, (I felt) I was able to take revenge by doing something I like,' he added.