Market share is a quantity ratio. For me it is not important that a lot of people use Linux besides me. But it is very important who uses it. That is because this is not a consumer good with buyers and sellers, and therefore this not a market. Important is that competent people are using Linux, because that guarantees that it gets better every year, which it does since I use it for 30 years. From my personal experience the most competent IT people I met were using Linux.
