You have a short memory. Netscape Navigator 3 had a >75% market share. Mozilla, which became Firefox, was a total rewrite, but that rewrite was done by the same people and was released as Netscape 6 - 9.
A majority of early adopters (of computers and internet connections in general) running some early version of this doesn't seem very relevant. I really don't think this ancient history (browser history does not go back much further than this) is working against Firefox today.