It is. It’s practically the most commonly owned pistol in the United States. Well, there is some argument as to what constitutes a “true” 1911, but I’m speaking in the sense of 1911s and all the clones and only fractionally different variants. Though Glocks and Sigs are catching up, they’ve still got some ground to cover to get there, and with the cheaper variants of 1911, they don’t really have the advantage of a price difference to help them. Plus, unlike Glocks and Sigs, the 1911 comes in tons of different styles and variants, for basically every price point and desire, from $4-500 basic models, all the way through to fancy-as-fuck $1500-2000 high-end models that come set up out of the box with lifetime guarantees.
And honestly, it’s kind of understandable. They’re simple, reliable, comfortable to shoot, reasonably accurate. both parts and ammo are relatively cheap and trivially available, and for the folk who carry day-to-day, despite being a full-sized pistol, they’re slim enough to easily carry concealed.