He did it because he wanted to.
Agree.
His parents are also responsible. He used the family living room as his bedroom. The space looks dirty and messy (pictures online) stacked with Amazon boxes. The parents knew about his hateful and dangerous behaviour but failed to check this room and were unaware of the knives, machetes and ricin stored in his bedroom? Right. The ricin could have killed 12000 people. He had manuals to prepare the poison and studied how to best use such weapons. If you know your son violent intentions as the dad did, why did he not ensure that there were no knives available to him in the house?
He is also reported to have had obsession with white genocide.
His parents are from war torn Rwanda and whether they were victims or perpetrators or a complex mix of both, they would have been deeply traumatised and affected for life. As a second-generation immigrant, I’ve seen how kids and grandkids of immigrants often struggle more than their parents. Balancing two cultures, being exposed to racism and carrying the weight of family history can be tough. So, anyone parroting but he was "born in Wales" is either naive or intentionally ignoring the bigger picture.
His parents carried the very recent trauma of genocide, and life at home must have been influenced by that brutal inhumane experience. The pain of his parents' past must have shaped their lives. [deleted edit fail]
AR is said to be autistic with high functions aspergers. He presumably was quite bright and perhaps violence, genocides, tyrannical systems and terrorist groups became his special interest. He was said to be a social recluse form a young age which is why his parents sent him to drama club and how he got to be on the BBC Children in Need video. He consumed the most depraved violent content online.
He most probably did experience racism, many students from migrant families sadly do but the majority do not then murder innocent people in retaliation. Based on what is reported AR is a person who retaliates when he is wronged and that is why he beat up a fellow young pupil with a hockey stick. Feeling sorry for himself he hurts others to feel powerful and in control, he even told the police he was glad the girls were dead. He stabbed a 6 year old 120 times. In a frenzy. He is not schizophrenic and has not diminished responsibility due to mental illness.
He is simply and evil human being. We don't know know if it's nature or nurture, probably both. What does evil mean in this context? One that is out to harm others because he wants to and who has no moral scruple or innate empathy. Evil.
Prevent should be updated to target individuals who consume excessive violent content and make repeated and credible threats against innocent members of the public.