I write and give away free software. People have paid to come to my workshops. They've paid me to write more.
It's sort of like why would anyone pay to attend MIT, when you can watch videos of the lectures for free on youtube? Oddly enough, MIT is doing better than ever.
MIT has an IP-equivalent in the form of the exclusive right to tell people you graduated there. Plus a regular property right in who frequents the campus, and it's known that much of the value comes from the network one forms there.
It's sort of like why would anyone pay to attend MIT, when you can watch videos of the lectures for free on youtube? Oddly enough, MIT is doing better than ever.