It's interesting. I was just thinking a little while ago about the tendency for smart people to equate being smart with being right. A while ago I was mentoring a young colleague of mine and I warned him that it is often the case that when we experience one failed project after another, we tend to think, "People should listen to me. I've seen every way to make a project fail and so I know how to make a project succeed." In reality, unless you have experienced success you are unlikely to know how to create that success.
He replied with one of the most interesting things I've heard in a while: "But I have lots of good ideas. Not all of them can be wrong". I had to step away and think about that for a long time, but eventually I realized that, yes, he could be wrong every single time. The search space is huge. And the tricky thing is that it doesn't really matter how smart he is. He can still be wrong every single time because there are a lot more wrong answers than right ones. A lot of the wrong answers really look like they should be right too. Even to otherwise brilliant (though wrong) people.
In a similar vein, I think you will find that despite your great intellect and professional success, there are many, many areas where you are wrong. In fact, there are likely to be a lot more areas where you are wrong than areas where you are right. There's just a huge search space out there.
I have no idea if you are right or wrong about marijauna use. I'm am absolutely convinced that you would beat me in a debate on the subject (I can't even spell the damn word correctly). Beating me (or anyone) in a debate makes absolutely no difference to whether or not you are correct.
It's not like I am immune to the occasional (umm... possibly a lot more than occasional... :-P) egocentric outburst, but I have found that admitting that I am likely wrong actually improves my credibility. I mean a brilliant, internationally famous blogger with a CS degree might very well be right about the effects of marijuana on the brain. Researchers on the effects of marijuana on the brain may just have the edge though, despite a possible lack of comparative brain power. It's something to consider.