He also explicitly said he'd learned his radical ideas from 8chan in his final post there; and furthermore, there's good reason to believe his selection of travel destinations was already motivated by his far-right worldview of a 'Muslims-vs-the-West' conflict.

Lastly, it is a mistake to take a document intended as propaganda directly at face value; for instance, his claims of "ecofascism" on inspection seem to be more intentionally selected to inspire infighting between political left and right (one of his aims he claims to have regarding gun legislation) rather than motivated by any genuine concern for the environment; for example, his manifesto was devoid of environmental concerns unless we were to first concede a fascist obsession with racial birthrate disparites is an "ecological" concern.

His manifesto also included memes and copy pasta.He listened to meme music as he drove to the mosque, he said "Subscribe to Pewdiepie" before he shot the first victim.

The fact that he was a member of an online community that considered his views normal is extremely significant.

And you don’t think his manifesto is propaganda rather than a attempt at reliable narration?

Coming to “the truth” seeing the reality of the world at first hand is a much more stirring story than being radicalised by lies on the Internet. Plus it fits directly into all the other racist propaganda put out by white supremacists about the state of Europe and France in particular.