As I recall, in 1998 MS bundled IE with Windoze 98. They had been offering it as part of an add-on pack to Win95 for some time, while Netscape charged money for noncommercial users until 1995 and commerical users until 1998, when IE was bundled with Win98 and Netscape knew there would be no more paying customers.
From that came two things: An antitrust ruling in Europe against MS (for smashing the paid browser market), and the Mozilla Foundation. I have always assumed that the Netscape people, their business crushed by IE, produced Firefox for revenge and to stay in the field. I don't know their true motive, but they understood that to compete with IE they could not ask Win98 user for
more money, or Linux users for any money. They got funding from Google, which knew even then that MS would be a dangerous competitor and would seek to replace them online. I do not know if Google will now seek to defund Mozilla since they've got Chrome. If they do, the Firefox code still exists and can still be used.