Affordable vs. ultra expensive speakers - what's the difference?

The difference = a lot of money for about 2-5% improvement in sound.....

The curve of diminishing returns.

Will it sound $48,000 better?  No

Will it sound better than a $2,000 speaker? Yes

For the wealthy people, $50k means nothing. For the average joe, there are many other ways to spend that money for good usage. 

Sound systems need to have synergy with their components. A great sounding system could cost less than 3k in the used market.

Not everything in life can be measured or ranked in purely monetary terms.

Pride in ownership and the daily pleasure that an object may bring one applies to Audio equipment as much as it does to anything else, and as such cannot be measured by anyone other than the individual.

Top performance from 20hz to 20khz at full volume doesn’t come cheap.

Always buy used for half price.

I’ll relate two experiences that I think illustrate the difference. Both experiences occurred while demoing speakers - though at different stores.

First experience - I was listening to Paradigm Signature speakers (I don’t remember the specific model but it was their biggest and best and I’m guessing the year was around 2015.  I thought they sounded pretty nice - not great, They were in my budget at the time and under consideration.  I made the mistake of having the dealer move the speaker cables to another speaker - above my set budget. Everything else was the same (obviously positioning was a bit different - but it was a big room).  I came away discouraged as the music was so much clearer. What previously sounded resolving and full range now sounded congested and lacking impact. The different in mid range clarity was proverbially night and day.  I didn’t buy the Paradigms but came away with lesson 1 that you can get more by going upstream.  It’s not all fancy cabinetry.

The second experience came when at a dealer to audition some electronics.  The dealer was playing it through Rockports.  It would have been about 2018. The Rockports being played were about $30k according to memory.  I thought they were fantastic in every regard.  But, the dealer also had the model up. I asked the difference and he said “just more of everything”.  I had him play them. Again - same everything accept for placement.  The difference in price? Another $15k.  The dealer was right.  More midrange clarity. Effortless and musical. Two speakers from the same manufacturer - already expensive. Similar looking cabinets, too. And, the difference would have been obvious to anyone.  Had I the room and the budget, they’d be in my living room today.  

BTW - none of the above would have been revealed by measurements.  In all cases, the speakers were essentially full range and measure well. 

More expensive isn’t always better, but let’s not cheapen the significant efforts by some honest builders to make something better. It takes effort and skill.