i want to know why black people get offended when white people join the "black lives matter"?

They get offended over everything, because white liberals have taught them to inorder to divide this country even further than it is. If you try to emulate them that is "cultural appropriation". If you don't include them, that is exlcusion. If you hire too many for a low wage job, that is systemic slavery. If you don't hire enough that is bad too. They want all their cake 🎂 & eat it too.

Black people like who?

Because BLM is not what they claim to be.

As of 2017, African-American militants are making a bid, through the Movement, to take over power from Whites. That means they feel they cannot afford to trust ANY Whites.

But they don't join, they infiltrate just like they did the March on Washington.

Black people can't have anything without Sam sniffing around

As far as I know, they do not unless you think you know more about Blacks then I do being Black. Black Lives Matter had a specific message to law enforcement, right-wing media made it about racism against Whites as usual when you put the spotlight on what they do. That's not to say that there were not some angry people that joined the protest and were not in the mood for heckling and were willing to take things further but that's not what BLM stands for.

I want to know why you think it offends me. It doesn't.

no, its usually closed-minded stupid white people that aren't part of it that are offended by the black lives matter movement.

they think its racist or plays favoritism towards blacks, when in reality, its just a movement to go against the oppression of blacks by the police.

if anything, most blacks would find it a novelty or appreciate it if whites join them against police brutality, but the reality is that many whites are too blindly offended by the movement to ever join it

I would recommend to listen to the old Mike Jacksons song black or white - it's not about races ,just faces

It's a churf war on a global scale - rather hear both sides of the tale - it doesn't matter if your'e black or white and that doesn't help then perhaps you could ask them

--- also agree with the other answer - which is likely your own answer to your own question - just using a different tag