Many (many) years ago, I used the MS-DOS version of WordPerfect. It was what was on the computers at school and on my friends' computers (those who actually had a PC in their home). I was good at it and was happy with it.
Windows 3.1 came out and WordPerfect launched a new version for it. It was horrible! We used it at work and I was always frustrated with how I had to "reveal codes" to get any meaningful text formatting done.
When I bought my first computer, it was mainly for writing papers for university, so a good word processing application was key. At the store, I asked what other word processing programs were available and I played with Word 2.0 for a few minutes. It was beautiful! I went home with Word.
That may not explain why others went with Word over WordPerfect, but it explains why I did.