What makes an expensive speaker expensive

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. 

I would tend to agree with ricred1.  Some folks may not be in the US and understand the free market system though.  I full understand that part of the equation, but I'd think if you were on a board like this, you would understand it.  

Hi analoguvr,
Despite having the privilege to hear speakers that utilize various types of "exotic" materials for their drivers, paper implemented properly is still preferable to many listeners. High quality paper cones sound exceptionally natural. Personally I’d choose this option compared to an ultra detailed analytical sound. Paper cones and tubes for example never measure as good as their alternatives but they sure sound very much natural and realistic when done correctly. There are non paper driver speakers that sound very well without question, I just do not find them superior to top quality paper drivers.  Of course YMMV as is always the case. 
Charles,