1. Because Apple didn't end of life their user's investments (see Avid Xpress Pro).
2. It was cheap (FCP Studio $1.100; Avid Xpress Pro (existed at the time) $1.850)
3. It was shinny
4. Most of my freelance work is with low budget documentary, a majority of them use FCP
5. Avid had been slacking off on it's support of the Mac platform
6. No dongle
7. Walter Murch said it was good?
8. One word: COMPRESSOR
9. QuickTimes instead of MXF or OMFI files
10. Avid Xpress Pro was really, really buggy. Maybe it's better you put it to sleep.
11. Avid and Adobe told me not to.
12. Because YES you can do [that] in Final Cut Pro
AD YOUR REASONS TO USE FINAL CUT PRO!