Thing about multi-organ failure is that it's almost always a single organ that goes and then takes the others with it, sometimes within minutes. A problem with the heart or lungs will deprive all the other organs of oxygen, causing them to fail too. Failure of the liver or kidneys will flood the bloodstream with toxins that would usually be filtered out, poisoning all the other organs and causing them to call it quits. Don't think of it as multiple organs spontaneously going together, think of it as a very rapid failure cascade.
As others have said, long-term heavy drinkers can stay barely alive for decades. But huffing duster can kill you dead in seconds, you risk instant death every time you use it - the "high" is an adrenaline surge, basically the brain's panicked response to being deprived of oxygen (being drunk is actually similar, as the brain shuts down non-essential functions to survive being poisoned by ethanol which is some really neurotoxic shit). That adrenaline surge can cause a cardiac arrest, then it's over.
Cobes' only real risk of instant death from drinking is from either falling over and hitting his head or from passing out and inhaling his own vomit. Given he lives and drinks alone the risk of that is high, especially if it happens off-camera and nobody knows he's in danger. But the duster could just one-shot him.
As well as instant or gradual death, Cobes is at risk of being permanently disabled. The duster in particular could cause a stroke, infarct or aneurysm, and leave him as a vegetable needing 24/7 care forever.
