My backround: I have had many friends who smoked all the time, were occasional smokers, and who are against it hardcore.
I used to be in a group of friends in high school who smoked all the time, they bought it and pretty much always had some on hand. They would probably smoke once or twice a day at least. I've stopped hanging with them but still have some friends who are pretty much potheads.
The reason I stopped hanging with my high school buds is not because they smoked weed, but because I got bored.
Personally, I think it is fine if you smoke once in awhile. I have smoked probably 35-40 times in my life. By that I mean, I mean just a puff. I have probably been high about 10 times. Its like drinking, just becuase you have one beer doesnt mean you are "drinking" necessarily.
However, there is danger in such a drug. I got bored with my old friend because it became an obession. Always on a quest to get more weed, get high, and do nothing. They did the same sh*t constantly sitting around on a couch playing video games, giggle at stupid things, and order pizza. I know people knock the anti-drug commercials, but i think the most recent one with the kid just sitting on a couch is acurate. It is easy for people to become more and more of a user because its dangers are mostly invisible until its too late, and bam, you are smoking weed everyday and caught in a cycle. They would say, "I am not a pothead, I can stop anytime I want." , yet they became phycologically dependant on it and couldn't go a week without smoking. I knew some other people who developed a sleep dependency on the drug. Constanlty spending money on it and addicted to always wanting to get high. You end up hanging with people who smoke because you don't want a buzz kill around.
So in essence, everything in moderation. Once you own a bowl or a bong and find yourself constantly short of cash, it might be time to look at yourself.