Ok, Ill feed the troll....
Niche market share of Linux desktop systems is (using the lowest percentage of 1.68%) is between 24,000,000 and 58,000,000 systems depending on whos numbers you use for the total number of systems. (Not even going into the fact that the % of share is a guess and ranges between 1.68% and 24% depending on who you look at)
It is estimated that around 90% of those users build there own systems.
Although the market share is small, the numbers are big and to some companies well worth the investment to try to capture some of that share.