Why so many wilson alexias for sale

I would think that many who buy expensive items, regardless of the hobby, are well off enough that when the urge to buy something new comes up they don't need to give it a second thought, just sell the old and buy the new. It's not necessarily a reflection of the product.

Because Wilson has (had?) an excellent upgrade program from the Alexia to the Alexia II and many Alexia owners jumped on it.

Because they are poorly made speakers, way too much energy in the top octave.

Too fatiguing to listen to over the long haul.