[slyall]

I think it was a network effect. Around 1992 The free PC-based BSD distributions like 386BSD were at around the same level (if not slightly ahead) of Linux.

However in 1992 and 1993 there were some internal political problems in BSD land (which eventually led to FreeBSD spinning off) and the "USL v. Regents of the University of California" lawsuit also cast a shadow on the legality of the BSDs.

During those two years Linux kept developing, jumped ahead and basically grabbed all the mind-share and marketing share.

The BSDs have been playing catchup since. For instance with fewer developers they had problems supporting a wide range hardware so were not even an option for many.