Wasn’t Cathedral and the Bazaar originally published in 1999? Who was paying thousands of dollars a year for an OS in 199? And I think GCC was already widespread by then, no?

I didn’t start programming until a few years later, but for sure by 2002, it seemed to me a given that compilers were free. It was my impression that stuff like Borland was niche and that serious stuff like Java and C were free.

Not saying you are wrong, just your comment surprised me. Maybe I have a revisionist memory or maybe those intervening 3 years were quite transformational in the industry.

2002 was before the tipping point, IMO. Open-source software existed, but wasn't always taken seriously. Linux was still widely perceived as being a hobbyist OS unsuitable for "real" applications. A lot of the Internet still ran on Windows and commercial UNIX servers.
By 2002 I was at Arbor Networks, shipping security software to tier-1 ISPs, and if we'd shipped it on a commercial Unix (let alone Windows) people would have looked at us like we had 2 heads. The writing was on the wall by end of the first dot com boom.
The firm I was at in 1997 was shipping commercial software with GCC. There were expensive compilers, but you weren't required to use them. For Windows builds, I think we were Borland C++, which was hundreds of dollars. Sun had a pretty expensive compiler for Solaris that I remember using for hunting down memory leaks.