Wikipedia functionally ended the market for encyclopedias. When I was a kid I would go to the library and read an encyclopedia just to see what random knowledge was in there. Traveling salesman would sell encyclopedias door to door and they were hugely expensive. Then Encarta came along and it was mind blowing you could have all that information on some CDs. Then Wikipedia killed all of them and did it for free.

When computers began to take hold in middle class homes, one of the biggest gold rushes was to be the encyclopedia of choice on the computer, since consumers saw encyclopedia software as an obvious (and maybe best!) use case for a computer.