We don't need to recreate reality. We don't need bright sunlight in dim living rooms. Typically when it's that bright outside (direct sunshine) we draw the curtains or wear sunglasses. Again, the pupil dilation thing - if ambient light is low, peak light needs to be lower to be relatively bright enough without being painful.
Set your phone to maximum brightness, sit in a darkened room with the phone off for a while, and then set it playing a desert movie. The brightness relative to your pupil size will be plenty bright enough at a few hundred nits.
The only time 10000 nits is needed on a display is when the ambient is bright enough that you need 10000 nits to be relatively bright enough. It's a lot cheaper and more environmentally friendly to just draw the curtains and dim the lights than crank up the display brightness.
But that’s really missing the point, and it’s understandable if you haven’t had much experience with HDR viewing or with trying to understand why it looks so much better. Which is also why it’s a bit of a hard sell to begin with.
I like to think of GOOD HDR as the way to get rid of a kind of uncanny valley in how we watch content on TVs.
Let me explain that. When we watch a movie for example, we know that what we’re seeing is ‘reality’. BUT! The TV only shows a representation of the reality that was shot with a camera. Colours aren’t really what they look like in reality, because in reality there’s a LOT more luminosity that has nothing to do with what we call brightness, but has more to do with how light behaves. In SDR or low brightness TVs, “Light” doesn’t looks like LIGHT. It looks like a white surface, and that’s not what reality looks like.
Now, try to think of HDR as a way to get rid of the limitations of the TV. A way to make the TV look more like a window into reality than a picture on the wall where light=white.
This has - again - nothing to do with blinding light, or looking directly into light sources, which will always look WAY brighter than 10,000 nits. You see the difference in every surface that bounces light. That’s where the magic happens. HDR makes the image REAL and 3D just from the surfaces reflecting or bouncing any kind of light: walls, metallic surfaces, any surface really. And as soon as you open this Pandora’s box, you can see exactly where the limitations are, as any bright part of the image that doesn’t feel right, doesn’t because there isn’t enough luminance (nits) and isn’t represented right.
That of course assumes that the content itself is mastered right in HDR (its not always a given).
So the WOW relating to this crazy 10,000 nits TV is due to the fact that finally a video of a car under the sun looks like A REAL CAR UNDER THE SUN and not a TV showing a car under the sun with colour and white surfaces trying to replicate the reflections and specular highlights.
This applies to ALL images, no need to have such a bright source of light as the sun- that was just an example. Everything in HDR elevates the picture from a ‘picture’ to reality.
I honestly have no more ways to explain it.
