"my primary issue with this is that many young, suburban white kids have been co-opting Black culture since the early 90s."
I'll accept that if you're willing to agree that blacks have been "co-opting" Western culture by wearing underwear. 😀
"I don’t know what specifically you view as “culture"."
The primary expression of culture is language; secondary expressions are clothing and personal decorations such as hairstyles. In all three areas, the blacks with whom I am concern differentiate themselves from mainstream culture with their own cultural cues.
For example, Black English is so distinct from American English that speakers of the latter dialect sometimes have difficulty understanding speakers of the former dialect. That in itself is a major marker of cultural differentiation; recall the biblical tale of the Israelites using the word "shibboleth" to identify their enemies.
Successful blacks speak American English. They might be able to also speak Black English, but they do so with an American English accent. Yes, Black English has its own distinctive accent.
Clothing is not as differentiated as language, but it is still distinctive enough to be recognizable in many cases.
More important is personal decoration, especially hairstyles. Obviously, the physical differences in hair have a strong effect, but successful American blacks have had no difficulty adopting hairstyles that fall within the mainstream of American culture. See, for example, the hairstyles of the three successful blacks I mentioned earlier.
I agree that the use of drugs is not a significant factor differentiating black culture from mainstream American culture.
You point out that some white kids ape some elements of black culture, and yet go on to successful lives, suggesting that this contradicts my claim that black culture is a primary factor in the poor results for blacks. These are the factors of black culture that are most significant for this discussion:
First and foremost is the pronounced rejection of mainstream American culture. Language, clothing, and hairstyle all scream to the world "I'm not one of you! I'm different!" This triggers xenophobia among members of the mainstream culture. Immigrant cultures have all embraced mainstream American culture, working hard to master American English, and dress like mainstream Americans. They are quickly embraced as "just as American" as others. But blacks prominently display that they are NOT mainstream Americans. As a consequence, they aren't treated as members of the culture -- which is a sure path to failure in the culture.
Secondary to this are some unfortunate values rampant in the black community, the most serious of which is the refusal to commit to educational success. The reasoning, of course, is that education can't accomplish anything against racism, and there remains some truth to that, but the enormous success of blacks who have pursued their education demonstrates that racism is no longer capable of blocking personal advancement in many cases.
A tertiary factor is the weakness of family bonds in the black community, especially with regard to child-rearing. See:
The conclusive argument, again, is that blacks who enter mainstream society (speaking American English, dressing in accordance with mainstream standards) have been quite successful, while those who retain the elements of black culture fail. It’s not the color of their skins, it’s the culture they embrace.
“The poverty rate for native born and naturalized whites is identical (9.6%). On the other hand, the poverty rate for naturalized blacks is 11.8% compared to 25.1% for native born blacks, suggesting race alone does not explain income disparity.”