I wouldn’t call that it’s only success. It’s an application that’s been used and maintained for 40 years. It’s the application that practically spawned the Free Software movement. It’s one of the most portable programs I’ve ever seen. The basic interface has been cloned (with less malleability) dozens of times.

It may not be the most used text editor today but overall I’d rank it one of the most successful applications in history — along with perhaps Netscape and Excel.