Brittanica went bankrupt in 1996, long before Wikipedia was a crowdsourced gleam in Jimmy Wales’ open-access eye. In 1990, the company had $650 million in revenue. In 1996, it was being sold off in toto for $135 million. What happened in between was Encarta.
Not because Encarta made Microsoft money (it didn’t), or because Brittanica didn’t develop comparable products for CD-ROM and the web (they totally did, with the first CD-ROM encyclopedia in 1989 and Brittanica Online in 1994). Instead, Encarta was an inexpensive, multimedia, not-at-all comprehensive encyclopedia that helped Microsoft sell Windows PCs to families. And once you had a PC in the living room or den where the encyclopedia used to be, it was all over for Mighty Brittanica.
When Wikipedia emerged five years later, Brittanica was already a weakened giant. It wasn’t a free and open encyclopedia that defeated its print edition. It was the personal computer itself.