As a non-smoker living in a country where marijuana use is still illegal, all I can do is go by statistics and empirical research.
Worldwide deaths from alcohol, per year: >3 million (includes drunk driving, drunk drowning, etc)
Worldwide deaths from tobacco, per year: >8 million (includes second-hand smoke, which kills about 1.2 million per year)
Worldwide deaths from marijuana, per year: Too low to be statistically measured, apparently
I did find an article making an estimate of 30,000 potential deaths from marijuana per year based on the number of users, but... it assumed an identical death rate to tobacco, which several decades' worth of empirical research has shown simply isn't the case. While breathing in marijuana smoke does have an effect on the lungs' ability to extract oxygen from the air during the actual act of smoking it (since, you know, the smoke takes up space in the lungs), unlike tobacco there appears to be little, if any, long-term build-up of toxic substances to cause cancer or reduce lung capacity (the lack of tar in marijuana, unlike tobacco, is a big factor).
Responsible marijuana use appears to have a death rate hovering around 0 per year. Looking over a bunch of different sources, I was able to find a grand total of two deaths directly attributable to marijuana itself... and those consisted of two young men (23 and 28 years old) who were both suffering from serious cardiovascular issues, one from a birth defect, the other due to a long history of heavy alcohol and drug abuse. Both died due to heart complications while high. All in all, it appears that unless you have severe cardiovascular issues - the kind that may well kill you just from walking up a flight of stairs too fast - marijuana can't really kill you all on its own (biochemical research indicates the needed amount to cause an overdose in humans is significantly higher than the total intake over an average marijuana user's entire lifetime; in other words, unless you're a multimillionaire or a very determined grower and chemist you're gonna have a hard time even acquiring the amount needed to kill you in the first place, let alone be able to smoke it all fast enough to do so).
That said, there have been a number of deaths (estimates appear to be less than 1,000 per year, world-wide) due to people walking into traffic or falling off balconies while high or from being poisoned by added chemicals (primarily pesticides) in low-quality marijuana, or in rare cases becoming suicidal while high due to ingesting high doses of marijuana while having preexisting mental issues. Again, not directly caused by marijuana itself, but still noteworthy.
While it could of course be argued that the number of deaths per year will rise as marijuana use becomes more common, at present it appears to be one of the least deadly drugs out there, whether going by total deaths or deaths in relation to number of users.
At the same time, the CBD in marijuana has shown itself highly effective in treating a variety of diseases, including some that are normally lethal. That said, you don't actually need to smoke marijuana to get CBD; you can just buy CBD oil or pills (from reputable sellers, of course).
So, yeah... authorities going after marijuana use while freely allowing tobacco use is a lot like Superman going after jaywalkers while ignoring the massive asteroid that's about to render Earth uninhabitable (it's called illustrative hyperbole, people, don't take it literally).
