Where does "MidFi" differ from "HiFi" or "LOFI"?

I have a totally different take on this.  Breaking down these categories by price point is basically another kind of objectivist approach.  The High End or whatever you want to call it differentiated itself originally by its focus on sound quality and I'm sticking with that.

High Fi - companies that place primary value on how their equipment sounds

Mid Fi - companies that focus on marketing features, cosmetics, prestige

Low Fi - PA gear, generic soundbars & portable speakers

I'd say pretty much everybody on this forum is philosophically High Fi; just being here is sort of self-selecting.  Note this definition allows you to spend over a million or under a thousand, believe solely in measurements or listening or just reading the brochures to choose.  We all have this one thing more in common with each other than with the vast majority of people, who are happily Mid or Low Fi

it differs in the ears of the beholder ... 

As others have noted, ignorance is bliss, but once you've heard the good stuff it can't be unheard, so now the bliss is gone. And yet: 4 of every 5 remain perfectly satisfied telling their "smart speakers" to play X. The fifth one becomes the audioholic.
Same thing happens in relation to wine. You give them their first taste of the good stuff -- well-aged grand cru Burgundy, single-vineyard ancient vine Albariño, etc., -- and they can tell it's special, yet they remain perfectly happy with same-day, grocery-store plonk for the rest of their lives. Only one in five is smitten. So it's not torture for all. Those posting here are the ones who got the bug. 

Interesting thread. I’d like to see what brands everyone thinks should go into each category. 

Midfi is where I am, Hifi is what I can't afford, Lofi is where I started.