> getting real 4K detail requires a level of precision in camera focus that frequently just isn't happening.

100% agree. Relevant examples: "The Batman" (2022) a gorgeous film which was shot with ARRI ALFA anamorphic lenses, intentionally modified and detuned to achieve a specific, "dirty" look and character. Blade Runner 2049 (2017) with Roger Deakins winning the Oscar for best cinematography even though he intentionally chose to shoot primarily on the Arri Alexa XT, a native 3.4K resolution camera. And the BR 2049 4K UHD is widely considered a reference grade disc and one of the best examples of what the 4K UHD format can achieve, despite technically being a 3.4K upscale.

And a personal example, this year's Superbowl broadcast, which was produced and distributed in 1080P HDR10, looked shockingly good on my 150-inch calibrated screen, which was enabled by a combination of best-in-class cameras, lenses and production talent with a high bit-rate throughout the distribution chain. It turns out when your primary cameras have $85,000 Canon glass on the front, it makes a difference (especially when Canon has a team of techs on-site all week to custom tune the lenses). Canon also loaned them a couple prototype super long lenses able to instantly switch to a shallow depth of field mode with zero change in aperture or shutter. One of those created a shot that made me literally rewind my DVR and pause just to appreciate (and then go look up how they did it later) It was a beautiful close-up on one player's face full-screen with perfect soft bokeh from a camera at least 150 feet away. Incredible.

> if you watch on a projector, 4K can be nice

It's interesting because I upgraded from a very high-quality native 1080P DLP projector (with pseudo-4K pixel shift) to high-end native 4K laser only about 18 months ago (fairly late). I never saw pixels on the 1080P projector except when displaying test signals during calibration (and even then, barely). I'm glad I waited a few years for 4K laser to more fully mature because, while there was an uplift in overall image quality going to native 4K, it was almost disappointingly minor. Even having waited so long, I feel like a meaningful portion of the 4K upgrade cost was wasted. Frankly, I'd still be perfectly happy with the (very good) perfectly calibrated 1080P DLP projector that's now nearly 7 years old.

If I was going to put more money into my AV system (and I'm not... because it wouldn't make anything look or sound any better), I'd invest in an even better projector lens. But that wouldn't matter unless Hollywood started releasing higher fidelity content. And even if they did, it wouldn't matter because there's no way to get a bunch of that higher fidelity content on my screen. Hollywood's not releasing anything beyond 4K HDR10+ UHD discs anytime soon (and maybe ever) and streamers don't want to distribute content at scale beyond 20-25 Mbps. OTA broadcast content could deliver slightly better fidelity (in theory) once (if) ATSC 3.0 ever rolls out widely but broadcasters have already made it clear they're going to divide any extra bandwidth the FCC gives them into more shopping channels at low bitrates. Frankly, I think we're pretty much at the end game for source quality in cinematic content for theater or couch-mode viewing. Now the only remaining battle is getting more people upgraded to gear, calibration, signal path and source content which can fully and correctly display what properly encoded high bit-rate 4K HDR10+ already provides (I include Dolbyvision in that because, in practice, it's pretty much the same quality as well-encoded HDR10+).

I also agree with you that it's hard to even see a noticeable difference between good 2K and 4K except with synthetic content like CGI animation. I think people who report observing a significant difference are either having some placebo effect or something was wrong with their 2K setup, signal chain or content, so 4K looked better not due to the resolution increase but because it fixed whatever was wrong with their 2K setup.

> Spending money on brightness and contrast is 100x more important.

Indeed. And also HDR, higher quality source content (ie less compressed), getting rid of digital keystoning or any other subtle degradation in the signal chain and, of course, ambient light control. I always tell new projector owners to first leave their projector turned off, darken the room to viewing mode and then sit there in the dark staring at their blank white screen. Then I point out, "that white is the blackest black you'll ever see". And that will (sometimes) finally convince them to get serious about light control. :-)

And then I walk by the row of 65 and 75 inch screens at Costco advertising "Amazing 8K Upgrade" to people who watch streaming movies from their couch 8-feet away from the screen and just shake my head. They're hawking grade-A homeopathic bullshit to nice people who don't know any better and should feel bad about themselves for lying to sell people something they don't need.