there are just not enough people out there that have a combination of skills necessary to build a speaker that can do what a good high end speaker can do. I have built several speakers and have repaired dozens and I know first it takes carpenters talent to build the cabinet with the addition of knowing the size of cabinet for the drivers you are using and baffle step compensation and all of that, then you have to an expert at crossover design in order to build a crossover that will work perfect with the drivers(what order?, Zobel networks, etc.), Then after all of that you have to be a driver expert and know how to put together drivers that mate well together and will have the same balance with each other for coherence and seemless integration. Then you also have to be either a good painter or a pro at wood finishing or veneering to get the speaker to be appealing to look at.

Point is most people either don't want to or aren't capable of all the things I have listed here.