You don't use open source software because it's better (it usually isn't).

You don't use open source software because it's freer (it only sometimes is).

You don't use open source software because it's got better politics (it isn't always).

You use open source software because *it is the only option*. In the long run, if it isn't open source, it doesn't exist.

image source: keithstack.com

As someone who was a true devotee of FutureWave SmartSketch (which became FutureSplash Animator, which became Macromedia Shockwave Flash, which became Adobe Flash, which became Adobe Animator) my sorrow is incalculable. Every day I long for software I had in the 90s which I can't find anything as good as today.
@mcc I still remember how excellent and affordable Cool Edit Pro was until Adobe bought it, rebranded it as Adobe Audition, and made the price instantly astronomical.