What makes an expensive speaker expensive

Ctsooner I agree with most of what you have said except for your comment about an expensive speaker using paper drivers.  Paper is a great cone material and most of the speakers using paper cones always seem to sound more natural to my ears. And just because it is paper doesn't mean it's not high tech.  People who have a Coral 10 that needs a recone can attest to that, it can't be done. 
And as far as the folks who are saying part of the high cost is R and D, give your head a shake, there are no new developments in speaker technology!!  The best speakers I have heard are still older efficient designs with paper drivers.
Just like 99% of high end audio megabuck speakers are a huge ripoff!  When I go to the shows I invariably never enjoy the high dollar rooms with the megabuck SS electronics. They are very detailed and some of them are impressive sounding but they never sound like proper music to me. 
And ctsooner don't take this as a slight against vandersteen, I think they are one of the few that actually do R and D and try to give you something for your money.  I enjoy them and used to own a pair. 

Paper cones can sound very good, but that does not change the fact that they are in total break-up at nearly all frequencies and therefore not an accurate diaphragm to excite the air in the room. Subsequently, the ear drum can't preserve an instrument's waveform. Most people think Bose speakers sound great and are totally adequate, but those who listen know they are not

It's a personal thing and I get that.  I won't be able to change your mind and that's cool. It's what makes the hobby part fun.  Most of the major and respected designers are working hard finding newer materials to make a pure pistonic moving driver.  

no speakers can be worth 50k.

any speaker over 25k are overpriced

I personally can and will never be able to afford a speaker over 25K, however making that statement that nothing is worth it is dead wrong.  It's proven to be wrong as we live in a society where folks control the market.  Plenty of folks are purchasing these and feel they are worth it, so they must be.  Maybe to you they are overpriced and maybe to you over 50k isn't worth it, but the market sure thinks they are and personally I am happy as the trickle down has helped speakers in MY price range of under 15k sound THAT much better.  

This is a discussion as to why speakers cost what they do not if they are worth it or not.  

Cost is what the market will allow. I've heard several speakers that are over 50K and if I had the money I would buy them.