Although the megapixel fetish race is the one that gets the most attention, I think the ISO equivalent is also pretty amusing (in a "shakes head, looks baffled" kind of way).
Now, I should preface all this by mentioning that I don't have a "genre" of photography. I just photograph whatever attracts my attention at any given time, and that can be day or night.
Recently I saw a camera review in which the reviewer was showing pictures captured at ISOs that would have been considered witchcraft even ten years ago. They looked like garbage - noisy as anything and generally an aesthetic mess. But apparently the fact that they were taken at stratospheric ISO levels means that the whole world must see them because, I don't know, reasons.
Although I've used cameras that are well known for good high ISO performance, a look through my Google photos collection shows me that I almost never go beyond ISO 3200, and I would guess that less than 5% of my (tens of thousands of) photos are shot at that sensitivity. On a usual day, I find that if I have a fast lens (F2 or quicker), I can get almost anything I want to shoot without going past ISO 800, or 1600 in a pinch.
I'd be interested to hear from people who do use these 5-or-6 digit ISOs on a regular basis, and what they shoot that necessitates these ISOs. Let's hear some thoughts.
You sound like a pretentious prick. I'm not demeaning you, just letting you know how you sound in case you want to change it in the future.
You sound aggressive and presumptuous. I'm prepared to stand by my statement.
Go on then. How do you "learn lighting" in an environment you cannot control?
You learn by doing and recognising. (I know, summing it up like that is a bit of a cop out.) You learn to watch people's actions, by seeing contrast in what light is available and learning your own limitations of motions vs shutter speed vs what your subject is. (It's not always formulaic.) You learn what makes a bad image and redirect your efforts to what you learn is a good opportunity. If you have to get the image under terrible conditions, because the client needs it, you just get it. If you don't, you can safely pass it by. You introduce strobe lighting when you can - providing it doesn't disturb the atmosphere of the job at hand (like a wedding in a church). And you invest in lenses before bodies, as always.
And sometimes, the thing you can control is ISO. If the choice is push the ISO or not take the shot, you push the ISO.