In my examples, friends went from marijuana to the couch or the fridge or a concert maybe, not to death drugs. Being in musician circles back in the day I saw many examples of this. I've seen ruined lives from alcohol and pharma etc, never pot. Interestingly I've known 3 that have died from a heroin overdose and none of them really liked pot. They were all ööööed up for a variety of reasons. That's what lead to their death. The most recent, if there was a gateway it was oxy - once the scrips ran out and became harder to get it was either take what's available or suffer through withdrawal and they weren't exactly strong of mind or will. The system was no help, not that it necessarily should've been, but this was a crash course of destiny and had absolutely nothing to do with pot. People do destructive things because they are ööööed up for some reason or the other, not because they smoked weed.
If someone destroys themselves on alcohol, well yeah, that sucks, but it should have no bearing on whether or not I enjoy a few pints here and there. I'm responsible, they are not, why does that have to become my problem.
The argument comes down to freedom. If someone shouldn't have the freedom to smoke weed then they also shouldn't have the freedom to drink, smoke, eat fast food or do anything else that might be harmful in any way as decided by our wise government overlords. It is an impossible standard and a tyrannical one at that. It's illogical to single out pot and leave the others untouched when the death numbers alone are nowhere even close.
You stated that you thought MJ should be illegal but what about alcohol and tobacco? I know you said they are being attacked, but that's not the question, do you personally think alcohol and tobacco should be made illegal as well? If so, fine, that's a consistent argument at least, otherwise, it's a total bullshit position, at least for the stated reasons.