...I'm a mixed race person who grew up in the Bible Belt - the kind of places where KKK rallies happened and still happen - and I'm not sure where anyone gets this idea. I knew quite a few proudly racist people and none of them cared about this. Does anyone think sexist men care about women calling ourselves bitches or hoes or sluts? Does any able-bodied person who mocks and beats disabled people care if we call ourselves cripples or spaz?
I'm not talking about in the modern day. In the modern day I don't think they particularly care (until they're not allowed to say it 
). But in the original days of the reclamation, people very much did care. It was quite a revolutionary idea and it did piss people off. It still kind of does, in a more mild way. People often get very upset when they're told they're not supposed to use the n word, as evidenced. I remember watching a straight girl eventually burst into tears after greeting a group of LGBTQ+ students as "f*ggots" and being asked not to refer to them as such! When the argument developed she began to cry and complain "it's not fair"...
I don't think word reclamation has anything to do or any impact on hateful people, it might help take the sting out and attempt to rebalance power but as we can see from the use of those words today, it doesn't do a very good job of it.
No? I'd argue that a whole generation hearing the word first from a friend, or from a song like 'Lemonade' - which I've now referenced twice, I know, but is such a fantastic example - is fantastic. These kids are still aware of black history, but now they've not only accepted the horrific racism which has impacted their past and even their present, but they've reclaimed it and now they've got it as part of their identity - and not necessarily a negative part. The fact that they've understood the history of a word, taken back the word and now transformed it into an embodiment of the solidarity and community between black people racists of old (and now) tried so hard and maybe sometimes succeeded to break - it's impressive, and I can completely see the value in that, even if it's not something I'd like for myself. The amount of support in the black community I see with the younger generation is not something I saw in the older ones, certainly not to this extent, and I think it's wonderful. "Blackouts", the #blackexcellence tag, #melaninpoppin', all of this - they try so hard to uplift one another and I love that.
Modern history showing how it's being used by black people against each other just shows how ridiculous we've become and, in my opinion, a laughing stock to others.
How often is it used really against one another, though? When (some) black people reclaimed the word, the definition obviously changed. It's not necessarily a sword they're wielding against one another. It can be just a way of referring to a black man, or in some contexts, just a person (I understand this generally happens in memes, which I'm not very up-to-date with). But often it can be an expression of identity and solidarity - something, as I raved about in my earlier paragraph, that I actually adore.