From what I’ve read, it’s due to the fact that they’re strapping a mask to their faces. The exhaled gasses have nowhere to go, it mixes with the inert gas, and doesn’t cause a loss of consciousness as quickly as intended.
Even if they managed the exhaled CO2 correctly (wtf they didn’t?!), that requires the CO2 to actually be exhaled. But someone who doesn’t want to die that’s being killed by asphyxiation is naturally going to hold their breath, which means the CO2 stays in them, ruining the whole point.
Inert gas seems like a great choice for a self elected procedure, but could probably never go well for execution, because the theory of why it works (asphyxiation without the CO2 buildup that causes pain) requires cooperation.
“Energy demand for this unnecessary thing we invented is infinite, so we might as well give up on managing energy unless the thing that demands infinite of it can manage it for us. What do you mean just don’t use the unnecessary thing that demands infinite energy?”
It’s not just evil, it’s stupidity.