The racism in 2019 white supremacists

In the beginning of 2019 one of the most bloodiest attacks ever happened in newzeland years
From one of the white supremacists called brenton harrison Anderson toward the muslims in newzeland
But why did that happen?
Maybe because of Islamophobia or what he grew up doing
Or the media
Without that much talking he written about 70 pages about his reasons why he did that on his fb page

But there's something weird happend that no body talked about that much if he was a guy pretending to be a muslim maybe it could grab more attention because of what
No body knows?!