Yes Brudda Eja
I don't know what practical benefit I get from believing it, cos as I said in the post I don't even "believe" it, I just think that it seems to be a plausible theory, supported by some amount of evidence.
It may very well be wrong. However, the evidence that I'm aware of, as I understand it, points towards it as a plausible explanation.
I know people who believe the human race started in Tibet, or India. Sanskrit is the most ancient language in the world from which all other languages descend, I was recently "informed." Since the person telling me this was an Indian descendant of Sanskrit speakers, I guess there was a practical benefit to her believing this... maybe made her feel important, or special, or whatever, perhaps. As for me, I chose not to believe it, not because there was a practical benefit to me not believing it, but because I am aware of no evidence to support it. As far as I know, the evidence points to humans migrating FROM Africa TO India, not the other way around (not until later that is). Also, the evidence points to there being languages in existence which have been around in some form or another for longer than Sanskrit has, and which bear no relation at all to Sanskrit, so there is no evidence that indicates that all languages in the world descend from Sanskrit.
To me, the main thing is that the oldest hominids, and the oldest humans, have all been found in Africa, and Africa has the richest continuous fossil record of hominids and humans, so it makes sense that hominids and humans originated in Africa. Maybe they ain't dug up all the fossils yet though. Maybe they'll find humans from 10 million years ago under the ice of Antarctica when it melts... but they haven't yet, so until they do (make some such discovery), "Out of Africa" seems to be the theory that best fits the facts as we know them at the moment.
No way does that mean white people therefore have some kind of "right to repatriate" to Africa! If it happened, it was 80,000 years ago, so that argument couldn't stand up in a court of reasoning.
I sight where you coming from about belief and knowledge, but when you say it's up to you what you choose to believe... well, taken to its logical conclusion that could mean you could choose to believe absolutely ANYTHING. Which, of course, anyone is free to do, but you know and I know that some beliefs are just plain wrong, so where do you draw the line? The only reasonable way I could think to draw the line is to base your [provisional] 'beliefs' on the amount of actual evidence you can sight for them, rather than how they make you feel or if you can immediately find a practical application for them. I'd like to believe that I live rent-free, and it would sure be practically useful to me if I did, but the evidence indicates otherwise.