You know there's plenty of antisemitism around the world, especially in places like Iran, which officially denies the Holocaust, that isn't coming from a "white supremacist" place, especially not in the context of American white supremacy.
Considering that we know for a fact that you don't know the ages, genders, nationality, or races of the people with these beliefs, and can only see their beliefs posted anonymously on 4chan, and then you think you have enough information to extrapolate that these people must be white, male, and young, says a lot more about YOUR prejudices than the people on 4chan, quite frankly.
You see hate and just assume the hateful are the gender, race, and age, that you perceive to be the enemy.
Considering that we know for a fact that you don't know the ages, genders, nationality, or races of the people with these beliefs, and can only see their beliefs posted anonymously on 4chan, and then you think you have enough information to extrapolate that these people must be white, male, and young, says a lot more about YOUR prejudices than the people on 4chan, quite frankly.
You see hate and just assume the hateful are the gender, race, and age, that you perceive to be the enemy.