Building from source is also just cooler. People be lookin' if you have blender I stalled, but can't uninstall it with your package manager. (Super useful)

Also, for tech noobs you can say "I built that".

No I compile my electron apps with -fno-electron

It is useful to be able to do. I've had a few instances where I needed to swap out some lines of code or change a build flag before a bit of software would work properly.

Install gentoo. Then you'll be building the defaults for the rest of your life.

Imagine using software where the defaults are good.

Not everything needs to be built from source, true, but certain software that isn't in wide distribution may have source as the only option.

Or maybe some tool hasn't been properly updated and errors on your computer, maybe you can debug it and change a small amount of source code to fix it. Maybe the source release is far ahead of the stable binary release and you want to test or use new features.

If you download the source for something like linux or ffmpeg or your favorite emulator, you will learn a whole lot by doing a deep dive.

However. Gentoo. Have you ever built firefox from source? That shit contributes to global warming. It takes so much time and CPU power to build such a heavyweight application from source and the tangible productivity benefit that you get from compiling on your own machine rather than downloading a binary is far outweighed by waste from the sheer active CPU and real time spent building. Maybe if you had a threadripper distcc setup, and only a dial-up connection to update source, it would be faster to compile everything than to get new binaries all the time. But for everyone else, if all you want to do is use the software, downloading binaries for the most popular applications is the way to go.

I can add debug logs if the need arise