With high enough voltage everything becomes conductive.

ElectroBOOM has a good video related to your question. He's demonstrating with a bucket of water rather than humid air but it shows what's needed to complete the circuit.

Please do not try this at home.

Electricity almost always transfers through the air and along the surface of materials. Air is considered an insulator because it doesnt conduct electricity very well, but it essentially acts like a very, very large valued resistor.

Given the voltage, you can calculate the distance through air a spark can jump using the breakdown threshold for the air. This is the distance at which the air breaks down creating a lower resistance path which lets more current flow, resulting in a large spark. For AC wall voltage this distance is extremely small, and even 100% saturated air will still have an extremely small spark distance.

In other words the humidity isn't directly a problem. The problem is condensation and corrosion, which could result in shorts, fires, and shocks, as well as electronics which fall into water or have a loose wire inside. Hair dryers, curling irons, etc can be dangerous because their heating elements can have live wires inside that could shock you if you dipped it in water. GFCI is meant to save you in cases like this by turning off the outlet.

Not on its own. You'd have much more of a risk of shorting out because the water condenses on all the surfaces.

Pure water is a fairly poor conductor, and the ions that make it conductive don't always follow the water into the air.

You can force it to be conductive by using a high voltage current, but a high enough current will make anything conductive, given enough power, so that's probably despite the point.

Short of super-saturating the air, it's probably difficult, if not impossible to make it inhospitable to breathe in with eager vapour. Water can only hold so much, and while you can increase the amount it can hold by changing the temperature, you'd be overheating the the traditional way at that point.

Maybe some extreme super-saturation of the air, so the water condenses in the airways? Although that's extremely unlikely, since it'll probably condense on the rest of the person, and the available surfaces first.

Someone DM William Osman.

As said in another comment, with high enough voltage, it's all conductive.

That said, in the space of a whole room, there's a lot of things going on. The electricity is trying to find the most effective single path to ground so, once you get to a voltage that can travel through the medium, it then has to navigate the entire room for that path, going through resistance at every point. By the time the charge gets anywhere, it will have been diminished to nothing. Also, paths and resistances will change unendingly due to temperature, dewpoint temperatures in air pockets, airflow, the content of the air that isn't water or air itself, etc.

Technically, being INSIDE water is being at maximum humidity so that personally counts for me.

I can think of a few things to point out here:

• water itself does not conduct electricity, it's the ions present in an aqeous solution that transfer charges. So humidity itself would be pointless in a case where the water droplets don't have charged ions present inside them.
• even if the droplets do have charged ions present, those ions would still need a way to transfer charges between those droplets through the air. That is only possible if either the air is too hot (basically plasma) or the charge density in the droplets is too high (essentially lightning, albeit a little different).
• another possibility for something like this to happen would be droplets condensing on exposed circuitry. If there happens to be live wires getting exposed through the walls, under the switches, or in an appliance, any droplets that get condensed at those spots would start conducting electricity (dust often has enough salts to allow such contaminated droplets to conduct electricity, but don't quote me on that). Do note that the atmosphere in the bathroom would still be safe, it's only the wet regions of the bathroom, like the floor and walls, that may conduct electricity.