Except Linux only took off thanks to those that didn't want to pay for UNIX, and the UNIX vendors that wanted to cut down R&D costs from their own in-house UNIX clones, and were uncertain if BSD was still safe to use with the ongoing AT&T lawsuit.
If you ask random dev on the street about .NET, there is an high probability they will answer it is Windows only and requires Visual Studio.
Red Hat was founded in 1993. When do you think they got the idea? When do you think companies like Red Hat decided to bet on Linux instead of BSD? Debian was founded in 1993 as well. When was that lawsuit settled again?
An awful lot of the Linux momentum that carries us to this very day appeared after the BSD lawsuit was filed and before it was settled.
What about the other “big and professional” competitor to Linux?
GNU HURD was started in 1990. The original plan was to base it off the BSD kernel. The Linux kernel appeared in 1991. BSD fell under legal threat in 1992. Debian appeared in 1993. RMS lost interest in HURD. None of these dates had much impact you don’t think?
They did not want to pay for big iron for sure, preferring commodity hardware. Even then though, many Linux boxes can get pretty expensive.
I think it is more about openness and control than it is about cost. Linux brings flexibility and freedom.
So does BSD of course. The timing of that lawsuit changed the world.