I agree in theory, but it is honestly hard to start your own WC company, especially if it is not retail but actual WC designing and manufacturing. Considering the rising costs of copper and cut throat competition, it can become very expensive and stressful as expenses mount while you try to juggle maintaining the company and build relationships with fabs and material suppliers. It would be great if new companies could pop out that easily and push competition and innovation, but that doesn't happen too often, at least not in the US.
Besides, there are still quite a few areas of the enthusiast market which haven't been tapped effectively by anyone just yet.
What it really comes down to is motivation... there isn't enough money in it to attract most entrepreneurial types and most of the enthusiasts either don't have the knowledge, resources, will/dedication, interest, ability, or some combination thereof.