Because I like to design and build speakers. Having them in use is easier than storing them.
I agree that you can make an excellent sounding system with two speakers, but I guess we do have some sort of weird addiction problem.
Here is how to put 19 speakers to good use.
That's eleven right there.
Here is another four.
And another four.
These three speakers are in storage, plus at least another two.
If you think I need intervention, I will see you in court!