The most-used operating system in the world has a Linux kernel. But, it might not be in front of you...except when you're checking email, waiting in line, playing Angry Birds, making a photograph, or checking up on Facebook.
I'm not a fatalist, I'm just pointing out a fact. FOSS is far from winning.
FOSS has barely "won" the lower levels of the stack and the highly technical niches. But the more you move towards user-facing applications, the more proprietary things become.
I am sitting in an office of 500+ Windows machines compared to 2 FreeBSD (and no Linux) machines.
I have to use Outlook otherwise I can't book meetings.
I must use Slack otherwise I can't communicate with my colleagues. (Or, alternatively, Skype For Business, but same issue)
"Free Software" is _not_ winning anywhere that isn't servers. (and they have fierce competition there too).