Consider what a blog is. It's a personal soapbox. It's a public outlet for your ideas and opinions. It's a way of communicating with people you wouldn't otherwise be able to, on your own turf (as opposed to on a forum where you have to play by rules set by others). It's a potential source of income.
Does any of that appeal to you? Ultimately there is no "should." You either want to, or you don't.
My blog hasn't helped me in the long run because I've only been regularly updating it recently.
But in recent months it's helped me to clarify a few of my beliefs and opinions, flesh out a few ideas, and begin a new (albeit long-distance) friendship. It's also shown me a path for further tertiary education that I hadn't considered before. A path which is more appealing than any of the others I'd considered.