To be fair, 6 million Jews isn't the same (in terms of cultural impact) as, say, 6 million Christians. Judaism is a much smaller religion. When 6 million Jews died in the Holocaust, that was 1 out of 3 Jewish people in the world. I've heard it described as the closest anybody's ever come to exterminating an entire religious culture wholesale.

The Holocaust wasn't a big thing just because lots of Jewish people died. (Let's be honest: We as a species are really really good at ignoring genocide.) Rather, it was big because a lot of Jewish people realized that not only was their religion the target of two millennia of bigotry, but that that bigotry left unchecked might mean the literal death of the entire religion one day.

I've heard it said that the reason so many older Jewish people are such staunch supporters of Israel, and ironically, why they're so willing to overlook its crimes, is that they feel they need to be militant in establishing a home nation for Judaism so that there will always be a place for Jews to feel safe. I think there's less anti-Jewish bigotry now than there was 60 years ago, but I don't think we've reached a place where that bigotry flat-out doesn't exist. So I can understand why they're so rabid, even if I don't agree with many of the things they've done to establish that country.