How is it an insult if they call themselves Nazi? It's a common shortening. Just like Sozi. I'm pretty sure that it was a thing within the NSDAP. And it doesn't matter, just to be polite I will use NS now.
It's a derogatory insult. "Nazis" never existed. Holywood propaganda working. Since you care about verifiable facts. https://en.metapedia.org/wiki/Nazi
It's just things we say to you since most of you are in fact pedos and groomers. I don't hate people who have mental disorders but I am not going to pretend it isn't so and give them their "rights" meaning molesting and grooming children, taking children from parents refusing to cut off their organs and subverting sociaty legally with help of law enforcement, having degenerate pride months every day...and affirming mental disorders are not disorders. I certainly wasn't talking about cutting you in any way. That is purely your imagination. I explained what we hate is your own weakness that you hate yourself. Hate is human feeling not crime and in this case purely justifiable as is hating pedophiles. If you want to ecuse anyone of hate for no reason you are barking at wrong tree, it's no one else than the Jews.
Discussion
They didn't. Read also the sources. It's true many NS people use it, we disagree among eachother here but as metapedia says this is our internal consensus based on facts such as Hitler never said such "shortening" in a single of hundreads of his public speeches, he pronounced lengthy 'Nationaler Sozialismus...'. Not single official document exists. They were National Socialists and NSDAP party. Yes it's common shortening. By jews.