More white people die in police custody because there are more white people in the UK. Of course there will be white victims of police violence, but in terms of proportionality the percentage of black victims is higher than percentage incarcerated, indicating that they face a higher than expected risk of brutality. Meanwhile other data shows that black suspects are more likely to face the risk of death or injury from police brutality:
Again, no-one is arguing that we shouldn’t stop terrorists because of racism. There is a debate to be had there, but this doesn’t change the issue of how blacks are treated by police.
The fact that you think you have the need to assert your ‘living in the real world’ is precisely what I mean by taking your head out of your backside. I can see why the political elements of BLM rile some, I just think that we should be able to separate acts of solidarity and raising of awareness from athletes and others from the less savoury aspects.