Chome's market share has come about because of Google's incessant marketing for more than a decade. Pushed on desktop with installers. Pushed on the search website. Pushed on YouTube by using Chrome's own standards that don't work with other non-Blink browsers. Pushed by sync. Default on Android which badgers you if you don't get a Google account. Default on school Chromebooks. And so on and so fourth. The miracle is Firefox's market share has held up so well.