I use it because it feels a lot snappier than other editors/IDEs I’ve tried when browsing large files.

Snappiness is definitely something I appreciate. So, if it blows everything else out of the water in this respect, that I might have to concede. Thank you for mentioning this particular aspect of it!

On the one hand, it’s a shame that it’s not open-source, but on the other hand, developers have to make a living from something.

I wholeheartedly agree. But, I prefer the capability to donate to the open-source software developers that I love to support.