> I will be writing in Word, or in LyX, or in RStudio, or in a text box.
You might still spend more time editing than writing, and Vim's modal approach makes editing more comfortable to me.
> Why is that worse than having a special key that goes into control mode? This is analogous to having caps lock, but no shift key.
The assumption is that modal editing is more comfortable and powerful. I can traverse the text and make modifications and replacements without holding chords between Ctrl, Alt and letter or arrow keys for long periods of time. Vim's model with text objects also makes some things easier to do than what you can accomplish with chords on editors liks VS Code.
If you spend a significant amount of time writing in all caps, you might benefit from having a Caps Lock key instead of shift.
> I don't want to do anything new. Why would I? I want to get on with my job.
Vim is something that's radically different from other text editors. If you think the learning curve is not worth it, it's up to you. It might not be; it's not like it will turn you into a better writer or programmer. But its uniqueness was enticing enough for me to give it a go, and I realised I enjoyed working with it.
> "if you try it, one day you will understand"
I don't think you should try Vim because it will magically make you a better professional. That's a fantasy some people use to justify the time investment they made to adapt to Vim. I think you should learn it if you're curious, and it's fine if you start learning and decide it's not worth your time. Have you never learnt something just for the fun of it?
PS: If you use VS Code or a JetBrains IDE, I don't recommend switching to Vim. Just do Vimtutor and go back to your regular IDE with a Vim plug-in. VS Code's is pretty good. This is the best of both worlds: you get all the powerful extensions and general IDE goodness while having Vim's Normal and Visual modes. As a bonus, you can still use the regular navigation and editing shortcuts while in Insert mode in VS Code. E.g. navigiating and selecting with Shift, Alt and Command plus arrow keys works like normal, so you don't need to switch modes for small things.