Linux was laughed at in the beginning by the Unix "pros". Now there's pretty much no Unix left anymore except Linux.
Linux doesn't really play an important role on personal desktops, but it's huge on servers where it killed pretty much all other UNIXes and that's a multibillion-$ market.
That's not actually true.
FreeBSD and OpenBSD are still going strong.
Playstations run FreeBSD.
iOS and OS X/MacOS are basically a Mach Kernel with FreeBSD userland and their own GUIs.
NetApp enterprise storage is FreeBSD.
There are other less-pro NAS/SAN appliances that are just FreeBSD + a gui (TrueNAS, FreeNAS, etc.)
A decent number of router appliances run pfsense...which is FreeBSD.
rsync.net runs on FreeBSD.
And....Netflix runs on FreeBSD. I'll remind you that it was the first thing that actually beat, umm...."spicy content" in terms of overall bandwidth.
Linux is insanely popular in the server world and does much better on desktop. But, BSD Unix, especially FreeBSD, is far from dead. The reason you don't hear about it as much is that the BSD license doesn't require that derivatives are open source, and it doesn't require attribution. IOW, you could literally download FreeBSD as-is, replace the license/copyright notifications and graphics, and re-release it as a closed source, for-profit product and be fine. You can't do that with Linux (even though some companies, like VMWare, do it anyway and pay the Linux Foundation not to sue them for it).
And...BSD Unix was 100% an academic pet project when it started.
At least personally, I have several more FreeBSD machines than Linux machines. It's definitely not just my iPhone and PS-whatever.