He's not a real person; he's a spambot. They post things on message boards, comment threads, anywhere they can. You notice how the posts are peppered with links? The idea is that the post will get picked up by Google, and then the links in the post will increase those websites' relevance score and will thus appear earlier in Google search results. And if some idiot is confused enough to actually click one of the links, that works for them too.
All of the random ramblings are copied and pasted from other, non-spam sources, and their purpose is to confuse spam detection software by looking like something legit in order to avoid getting flagged as spam.
I suspect that this user will get blocked by the site admins pretty soon; I'm kind of surprised it hasn't happened already, TBH.