What makes an expensive speaker expensive

But for every TAD, Wilson. Magico, and other six-figure speaker, there are 3- and 4-figure speakers that satisfy the listener to the same extent.

until they experience TAD, Wilson, Magico ...

Money make an expensive speaker more expensive. 

Quality of drivers,crossover and cabinet as well as were it is made and markup.

The difference between a very good expensive speaker versus a very good inexpensive speaker is usually size and ability to go full range in larger rooms.

In most cases, expensive examples of products generate higher gross margins than inexpensive examples.  A Chanel handbag may feature top quality materials and use skilled manual labor which drive up costs relative to mass market handbags, but the portion of the wholesale price representing margin is higher, too.  This also applies, to cars, cameras, and wristwatches. So, there's usually some element of higher price tags that can't be assigned to "substantial" differences.  However,....

Brand equity generates a return, too.  As a rule, people will pay more for brands they want.  A Lexus ES and a Toyota Camry aren't identical, but they are very close mechanically.  The interior appointments, Lexus buying experience and brand value all increase the price of the Lexus.  When aggregated, Toyota still makes more on each ES they sell than each Camry.

Bottom line, in almost all cases, it's a combination of things, including higher mark-up.

As to the likelihood of a $30k speaker outperforming a $150k speaker, there is little question in my mind that that is exactly the case.  Line up every $30k model on the market against every $150k model (blind) and I'll guess that most listeners will prefer one of the cheaper speakers to one of the more costly models.  On average, I may prefer the more expensive guys, but I'm pretty sure that the performance variations within each price range are pretty significant.  Significant enough that I can build a case for a cheaper model on some measurable basis - bass extension, on-axis response, power response, uniformity of dispersion, etc. - that it's fair to say it outperforms the more expensive competitor.  All you need to do is to prioritize that one performance parameter where the cheaper guy is better.  And, in the real world, measurable or not, most listeners do tend to prioritize some parameters over others.

Personally, if offered my choice of any speaker, I highly doubt that I'd choose a six figure model.