Hmm, am out of date with classifications, I think cannabis was a lowly class C when I last smoked it, in which case no I haven't.
I don't think most people have, no. People hang around with people who behave similarly, so will have vastly skewed ideas of normal, both ways. At university almost everyone I hung around with smoked dope and for most, that was all. Some did speed or acid occasionally, only a few went beyond that. There were plenty of other social groups who did not smoke or do anything at all and in numbers, they were probably greater, as they included most of the people you never saw, except in lectures.
I stopped smoking in my final year as it wasn't conducive to concentrating on studying which I got more into, I recognised how boring it makes people and I have a basic ethical problem with the supply chain - there isn't much organic, fairtrade resin available, there is a horrible chain of violence and links to serious criminality.
I suppose I think I'd like to take heroin once and only once - without any potential for fatal effects. I was getting all enthusiastic about the diamorphine offered during delivery, until I learnt about the nausea and 'out of it' effects, now not on my birth plan.