2018 exactly what is ‘High End’ audio?

There is plenty of "High End" equipment that is pure crap.....

High end means more expensive and exclusive compared to the rest, plain and simple.

To get people to buy it, there has to be perceived value to justify the cost. For high end audio that translates usually into some combo of bling, sound, and snake oil. YMMV.

I don't know how to discuss defining hi-end audio beyond my own (and therefore unique) personal experience.  So for "you" it's going to undoubtably be something different.  but i do know what anyone who loved their stereo system and/or even more significant- their love of music and their passion for sharing it with others really gets to the heart of things. As I met more and more people who invited me in and asked me what I thought of this or that album, it wasn't so much what they had to play it on (everyone had a different budget level and shopped different stores), it was their tremendous enthusiasm that impressed me the most.  
    Eventually I got to hear better and better stuff,  I could definitely relate to the YouTube video of 1950's Hi-Fi (thanks JMGROGAN) and remember browsing in department stores as a young kid looking at console stereo's (with built-in television sets).  When separate components came out on display in the 60's i swore i would someday get a nice stereo, too- Fisher, Scott, Marantz, WOW was i excited. One afternoon my dad and I got to hear a demo of  Voice of the Theatre speakers!  But... they didn't sound much like the real thing to my ears even though you could hear them three blocks away.
    Finally in my 30's I graduated from a Denon amp to a Hafler and then spent a "small fortune" and replaced it with a used Levinson.  
WOW all over again.  Instruments had real texture, and the notes took on a whole new dimension of liveliness. I was finally able to come up with the enormous amount of money it took, and that it was beyond my reach only a few years ago. I had felt guilty, embarrassed, even silly for wanting such esoteric gear just to listen to my CD's.  I just know how great the music sounds these days, and just accept how much I enjoy the experience.
    So nowadays if people want to know "how many watts" my speakers have, I'll tell them "100 each" and just let it go. But if they really like what they hear, I'll also add that "it's quality not quantity"....

High End, at one time, meant the components that came closest to mimicking the sound of live, UNAMPLIFIED, acoustic music heard in a defined space.
The problem is, too many people on forums do not go to live, unamplified music events, so there’s no way for them to know what is closest to the "musical truth." So they proclaim certain equipment "crap" without knowing for certain, that the setup and electrical compatibilities are not to blame.

I heard the ASL Hurricanes at Lyric HiFi in 2003. If I used that ONE audition to conclude the quality of those amps, I would have pronounced them unfit to be called 'High End.' However, I didn’t trust the audition, because the dynamic range was so bad, that after reading the TAS review, I had no doubt that that would have been a mistake to think that this is what the amps actually sounded like. And this, in a room with the IRS V speakers sitting nearby (but not hooked up for the audition). I looked over every piece of equipment in the system, and - except for the Dynaudio speakers - knew that the sound I was hearing just couldn’t POSSIBLY be the way it should sound.

So, I bought the amp, months later, elsewhere (and still unheard, except for the Lyric HiFi audition), set it up in my own system and listening room and turned it on - and was immediately dazzled by the utter realism of it. And by "immediately," I mean I pressed "play' on the remote control cd player over my shoulder,  walking back to the listening position. Didn’t even make it  to my listening chair (all of 10' away) before I whipped around, astounded, by the sonics. I was expecting, based on HP’s review, a certain "magic" to the presentation, but I got far more than I ever expected. To this day, I still have the amps. And I’ve heard higher resolution components but never anything with more "realism" than the ASLs. (I’d sure like to, but nothing I’ve heard over the years is akin to the realism they produce, although I can outlines their weaknesses easily). So, back to the point: mismatched components - and I have heard dozens of setups that I’d call 'mismatched, if only because the resulting sonic presentation was  REALLY mediocre - are all too often responsible for what people hear, rather than the component itself, at its best.  
And that is also why I only comment on what I have heard, not on the whimsical - or snarky - utterings of others who’ve never heard the component they shower such disdain upon. This is why so many others get it so wrong - and so often.
Even some inexpensive components come close to the "musical truth," if that includes tonal accuracy, musicality and dynamic range and contrast. They may not be the last word in sound staging, imaging, high frequency extension, etc, but they’re still truthful to music that was recorded in specific halls. In other words, Carnegie Hall, the hall I know best, sounds like Carnegie on recordings I know well (mostly older recordings, and BY FAR, on vinyl). But if you know live music, you know its rarely "boxy"-sounding, or the surrounding acoustics sound like it was recorded in a hall with a 20 watt bulb, and the dynamic range is...non-existent on the 1812 Overture.

Nowadays, people have hijacked the term "High End," to mean "expensive (which equipment certainly is, these days)! I don't place much faith in their opinions if they only refer to other components, never mention ANY comparison to  live music, or, AT LEAST recordings that have minimal manipulation.