Personal anecdotes of successful piracy don't make for an open-source license agreement, otherwise I would be a minor king of open-source.

If a database server's license says “only allowed to use for personal purposes”, it's rather obvious that I can't install it at my work. If a keyboard's license says “you may modify the software only for non-commercial purposes”, it's less clear, but also not apparent why the same interpretation shouldn't apply. Most importantly, copyright law doesn't allow willy-nilly use by default in the case of doubt.

I also changed some behaviour in my GPL editor for personal use once without sharing my changes and also I used that version a few times while writing proprietary commercial code

As the other commenter correctly pointed out, GPL only requires you to share your code if you distribute the compiled binary. And, being a fully FOSS license, GPL doesn't restrict commercial use of programs.