I'm confident Hubbard wrote "Message to Black People" and that specific quotation -- or at least that they (like a lot of policy) were issued under his name with his authority. I recall reading it more than once. It is also, if I recall correctly, something that is handed out at the Church of Scientology of Inglewood and the Church of Scientology of Harlem.
I specifically recall the language, "A professional Scientologist has more social standing and ability to help than any other professional field."
Also, the Cult Education website notes:
https://culteducation.com/group/1284-scientology/25135-xenu-goes-uptown.html
* * * * * BEGIN EXCERPT * * * * *
Hines, an older African-American man, presents a large portfolio with mock-ups of the new Harlem church, which is expected to open in the fall of 2008.
He points to "A Message to Black People," written by Hubbard in 1961, which states that black people must change their situation in order to take their place among the most brilliant on earth.
* * * * * END EXCERPT * * * * *
Similarly, the Scientology News article "Meet a Scientologist — Patricia Gore’s PhD in Making it Go Right" states:
Code:
www.scientologynews.org/press-releases/meet-a-scientologist-patricia-gore-2012.html
* * * * * BEGIN EXCERPT * * * * *
Since 1995, Gore has been a member of Ebony Awakening, a nonprofit organization dedicated to restoring dignity and self-respect in Black communities by eradicating drug abuse, illiteracy and criminality.
“
The group was inspired by Mr. Hubbard’s ‘Message to Black People,’ written in 1961 in the height of civil rights unrest,” says Gore. “His message invites Black people to use the technology of Scientology so our people can ‘take their place amongst the most brilliant people of earth.’”
* * * * * END EXCERPT * * * * *