IMO the problem starts right at the point where people consider "1 xanax" to equal a whole 2mg bar.
2 miligrams of alprazolam hit as hard as 40 mg of valium, or 4 mg of ativan. A xanax bar is technically designed to be broken up into 4 pieces of .5 mg, which would be a sensible daily dose for someone suffering from moderate to severe chronic anxiety. Note how in some nations, the maximum dose of xanax is 1mg per tablet, and the 2mg bars are either unavailable, or they are in a different schedule and thus rarely if ever prescribed.
Also, a significant portion (or virtually all, if you're outside the US) of the xanax bars on the black market are counterfeits, anyway, which sometimes means that they're *stronger* than the real deal: Bulk alprazolam powder is cheap as hell, as are grey-market "RC" benzos like etizolam or clonazolam, and there is a fierce competition among vendors on the darknet.
If you start off on 2mg of xanax, then a single 2mg re-dose would already be enough to put you into blackout territory. Heck, without tolerance, many users can reach blackout territory on 1 bar already.
At any rate, I fully agree with d1nach that the issue with xanax isn't about dying - although that can still happen, like when the xanax makes you forget about not combining it with opioids, or when you do a Houston and pass out in the bath tub. Benzo abuse can thoroughly ruin your social relations, get you fired from your job, or get you arrested for a DUI or all kinds of stupid shit people do when they're barred out.