[magduf]

>Otherwise, for instance, nobody would be debugging with gdb, rather than Visual Studio or what have you.

If you're working with embedded Linux, Visual Studio isn't going to be much help for debugging on a target.

>Nobody would be LaTeXing instead of using MS Word or Adobe Illustrator.

LaTeX does some things much better than Word, and Illustrator is very expensive.

>GIMP isn't as good as Photoshop (if I believe what people say), yet people still use it.

GIMP is free. Photoshop is not.

You seem to be assuming the people have unlimited money to purchase software licenses. Many free software programs are used not because they're better, but just because they're free and good enough. If I just want to crop and rescale some photos or something, why on earth would I buy a Photoshop license when I can just download and use GIMP for free?

[kazinator]

Many proprietary programs also get used because they are good enough. Not everyone wants to do a simple thing using some UI that has grown into a Boeing 747 cockpit.

Some Windows users use neither GIMP nor Photoshop to crop an image, but rather MS Paint, which is comes with the OS, so it is "no additional cost", and requires next to no training to use.

MS Paint has vastly diminished functionality compared to either GIMP or Photoshop.

[magduf]

Maybe cropping wasn't the best example for me to use, but there are many people who want to do more advanced photo editing than that (which is beyond the capabilities of MS Paint), but do not want to pay $$$ for Photoshop. Those people frequently use GIMP, simply because it's free and it works well enough.