Ok, here goes...
Well that is a very particular version of "high end" - sounds like the ultra expensive bracket that few audiophiles actually play in. And even there people of means could find rational justification in buying some super expensive gear. Like, if you can afford an MBL 101 Extreme speakers without any financial pain, then you are getting a design that is fundamentally different than most out there, very bespoke, with very high quality parts and finish, and if the sound and looks turn your crank...it's totally rational to buy such a system. In other words: you simply aren't going to find the same product cheap. Any number of super expensive speakers may fall in to that category.
My tube preamp cost more than my Benchmark preamp, but I love the look of the preamp, the build quality...there's some pride of ownership there...and I like the sound in some ways more than the Benchmark. An expensive tube preamp would be "silly" for some audiophiles, but rational for others.
There's always diminishing returns. But I'm pretty sure the Grand Utopias could blow away plenty of sub 5K speakers in various aspects, likely scale of sound, dyanamics, possibly sheer realism with various types of music. I mean, a stand mounted speaker with flat frequency response only goes so far.
I own speakers that are more expensive than some great-measuring speakers reviewed here (like some actives). But I compared them to tons of different speakers (including some that an ASR member might prefer) and I simply loved how these ones sounded in particular. Plus I preferred the aesthetics FAR more than just about any of the other speakers I looked in to (and certainly far more than any active I've seen). They have a super luxurious finish and build quality, a feature I never tire of since I'm looking at them in my listening room every day. I consider my purchase entirely rational for me, even if it's not for you.
"Better" can be situational, as well as subjective.
If someone very well off has gigantic hard to drive speakers, and he loves the cyber-punk look of Dan Dagistino's "Relentless" mono amps which will drive anything, then it's perfectly rational for that person to buy those amps. There's all sorts of pleasures that may go along with it. Even people here who buy Benchmark amps often admit they are paying for over-performance in terms of distortion specs vs what they could have gotten cheaper. But some get satisfaction from the engineering aspect as well.