Linux is regulated to the pure geekdom of tech history. Just 5-10 years ago businesses were considering Linux as at least web servers but now it's dying and has no future in business. It will be what it is or less as time goes on.
It will always be a toy of geeks. Not making a judgement on thats the way it should be, just stating the reality.
If you want to really learn to earn money.......... Vmware/SAN/Security/AD will get you the most opportunities in I.T. shops.
If you don't have a seat at the table, you're probably on the menu