You are doing the exact same thing I do. Taking your personal experience with something, and drawing your conclusions about it based on that experience. If you look at my college transcripts, my gpa went up over time, as did my marijuana use (I didn't start using it until the 2nd half of my freshman year). I rarely drink, so I save a lot of money because marijuana is a lot cheaper. Also, I am able to still function (mentally and physicall) under the influence of weed, I was not able to do this under other drugs and alcohol. I use marijuana as a reinforcer (I've created a thread about this in detail before). And again, from my personal experience, I know M.D.s that use it. I know company Executives that do. I know high profile laywers that do. All of that is goes into me forming my world view on the subject, just as your personal experience is what you use to form your's.
I go a step further, I realize that my personal experience doesn't generalize to all people, so I look for more objective sources. I took 3 college courses specifically on drugs and their effects on behavior and cognition. I've read more than one book on marijuana (the best one was written by an MD and a Ph.D. and draws from a wealth of sources).
Does this make me any more "right" then you? Of course not. Does this mean weed didn't have terrible effects on you and your family? No!
I think all it really tells us is that different people can be affected in dramatically different ways by the same sort of stimuli. This isn't unique to weed, the same principle is at play for many other drugs (legal or not) as well as non drug stimuli like music, movies, etc.