Because the fast majority of them whom marry out ITS NOT DUE to self-hate, or at least self-hate is not the underlying issue for her choice, the top 4 reasons are as follows.
1) She's late 20's early 30's over-educated and too old for Somali males, hence has no choice (make up the majority)
2) Divorced women (second majority group that marry out, may dislike Somali males because of divorce but it's not self-hate)
3) Low Self Esteem Lottery Girl (The Gypsie girl is an example, any Somali male could have easily picked her up instead, no self-hate their)
4) Self hate (make up a very tiny minority of the women, I know these, they usually end up marrying above their weight)
The worst choices you cite are made exclusively by groups 2/3 and sometimes 1 when the issue becomes desperate, the self-hate women very rarely fits your description, believe me I know a handful of them. They do not come on forums like these and want nothing to do with their people.
@Adolf-Hitler this is the answer to the question you were asking me. I agree with Inquisitive on this.