> if there is a leak the gas tanks (nitrogen, argon, helium) can quickly displace the oxygen inside and I'll die before I know what happened.

This is something so many people don't realize.

When you hold your breath for too long, that feeling of suffocation isn't caused by a lack of oxygen, but the build-up of CO2.

If you replace the oxygen in a room with an odorless gas non-oxygen gas, your body doesn't tell you. You don't feel like you're suffocating. You just start suffering the effects of lack of oxygen. Dizziness, confusion, lightheadedness, but you likely won't realize anything is wrong. Your judgement and ability to react goes away and you lose consciousness without ever experiencing the desperate urge to breathe.

Another good example of this is when pilots fly too high without supplemental oxygen or adequate cabin pressurization and become hypoxic. They become confused and lose coordination while feeling perfectly fine. By the time they realize something is wrong, they may no longer be able to do anything about it.