OK, this is an incredibly subjective question, but I'm going to pose it anyway.
What would make you more intelligent, attending the classes of a rigorous four-year college for a semester or reading some of the top influential blogs on a daily basis and blogging your responses for four months? I think that many in the "real world" (ie, people who probably definitely wouldn't read this blog anyway), would knee-jerkily respond that college is the obvious choice here.
But hear me out here. Reading many of the top economics, science, and political blogs over the past four to five months has been one of the most rewarding experiences of my life. Freakonomics and Marginal Revolution have taught me a love for data. Cognitive Daily and Mind Hacks help to reaffirm my belief in the importance of raw, experimental science. And reading David Brooks and Kevin Drum have kept me far more informed on the political scene than I ever was when I used to drone through CNN and the occasional Daily Show. All the while I'm actively learning, and reinforcing this learning by writing about these subjects on my own time.
Compare this experience with college. While Vassar is probably one of the most challenging schools in the country and I have had to engage in each of my classes to keep up, most of the talk among my fellow students is not about the issues, but instead about "beating the system." Respect in many cases comes not through understanding the material the best, but by getting the best grade while doing the least possible amount of work.
I'm sure that this sounds plenty pretentious, and rather rantish, by this point. But it's not meant to be. The point is, I succumb to this groupthink on a daily basis as well. It'd be remarkably difficult not to.
I'm usually not this forthright about the utility of blogging, and perhaps it is the stress of all of the work that is piling up on my shoulders that is forcing me into it. But the next time you fellow bloggers look down upon your writing as merely a hobby, consider the possibility that your supposed hobby might not be as trite as you assume.