It's a tiny amount--I'm guessing I've probably easily logged 20,000 hours of active use in vi by this point, I can't think of any other tool I use regularly that has a better time-of-use/time-of-setup ratio. Compared to the time I've spent, say, installing Ruby gems and fixing dependency conflicts it's a rounding error, and Ruby's only been a focus for a small fraction of my career. To clarify that wasn't ever one 20 hour chunk, that's a rough guess at the total time spent setting it up on dozens of different computers across many different operating systems and window managers. It's typically well under an hour of setup per computer, and much of that time goes towards remembering where to find installers, picking fonts, etc.