"There's nothing as much fun as making your own tools and your toys and taking the tools and toys that you have and making them better. [...] It is a singular joy to be a maker of things and be able to make your own things to make more things... it's spectacular!"
— Adam Savage (youtube.com/watch?v=nZAJKGHJy4)

It applies to the software development too, I think — especially to open source/free software.