My father fled Nazi Germany in 1938 at the age of 14. He lived through being in school in Germany, getting beaten up for being Jewish.
My father was interested in politics. He would follow it. I remember being with him once when he was excited about something that was happening in Israel. He said to me, "You know, the Holocaust could happen again." I asked him, "How will I know?" He told me to watch the newspapers, to see the language and politics and its impact on Israel and the Jews.
My father passed away in 1981 but I remember what he said.
If that is not reason enough, take a minute to watch: