Sweden has slowly been going insane right wing (and the rest of Scandinavia too, but more slowly). They failed to treat the Nazis in their society seriously and have allowed racism and conspiracy theories about immigrants and such to fester.
The right is in this for the long haul, too. When Anders Breivik (aka Fjotolf Hansen) blew up a bunch of people, who did he target? He targeted a camp full of future political leaders. He wanted to kill the next generation.
Every modern society has Nazis in it but you can't have a modern, advanced, peaceful society if they get any power. You have to fight them and their bullshit wherever they appear.
They also have a personal, psychological need to be "normal". They can't stand the thought that other people aren't like them--or maybe even more importantly: that they aren't like "normal" people.
Bob Altemeyer's The Authoritarians talks about this in some detail.