I suppose that you could even make the same claims about water too, but I think most of us would recognize the differences.
Something being dangerous to someone in and of itself isn't a good reason to criminalize it. Thaz all I is saying'. The same dangerous consequences of Pot can also be found in Valium and Hard Liquor. Same consequences and effects are the key part of that. Sure I could drown in water or get electrocuted in it, but it won't run me into a ditch or into another car head on. Those others COULD and HAVE. How many celebs have died from OD's on scripts or how many people have died from someone driving drunk? A LOT.
You could argue none of them should be legal based off the fact that it can have a serious effect on others. But then you go down a slippery slope. And that usually only happens when the user of any of them has made a poor choice on how they used it. It causing a detrimental effect IS illegal though - Assault, DUI, Accident. They could probably do the same with pot - make the pothead walk a straight line, run a test on them, etc. Just like anything else I suppose - all in how it is used and timing.
I think the big picture a lot of folks miss is that the moral argument is such a red herring. Forces unseen are behind a lot of the "keep pot illegal" rhetoric and pay a lot of money for it to be seen. hint hint - big pharma and tobacco companies. And they prey right off evangelicals and conservatives in the Bible Belt.