Then, somebody mentions this topic and I lose what friends I have :-(
You're wrong about that. :-)
This disucssion reminds me of a health/science class I had in middle school. We were discussing things like LSD. The guy behind me was telling me that cocaine was a great drug because it wasn't addictive. Lots of people in the 1970s and early 1980s thought that....
Like you, I've known a few people over the years who were really messed up by pot. I've known a few others who could smoke it occasionally without apparent longterm deliterious effect.
Illegal drugs and privacy issues (like the Santorum thread) cause some problems for me. Drugs clearly impair rational thinking and motor skills. But the harm of having them be illegal is something that's hard for me to unquestioningly tolerate. People should have a right to privacy, but obviously there are limits (e.g. you don't have the right to make $100 bills in your basement [unless it only becomes illegal when you try to pass them - but I think not]).
Don't take the disagreements personally. :-)
Cheers,
Scott.