Google's dominance is almost entirely due to the fact that its by far the best at search. I use ddg, but I use google search via !g about 25-50% of the time after a failed attempts. And 9 times out of 10 Google gives me exactly what I'm looking for. For instance: "the actor that plays the news guy in spiderman" ddg: Tom Holland (side bar) Spider-Man Homecoming (imdb) Tom Holland (wiki) Spider-Man: Into the Spider-Ver…
In the end, I think most people could use either Google, Bing or DuckDuckGo and be happy with the results. It's just that we're stuck on "Google is the best search engine", and while that may be true in some technical sense, many of the other search engines are just as good for most of us.