I evolved over the decades. I started out releasing most of my projects under a copyleft license. Then I switched to an open source license. Now, I'm mostly back to copyleft.

I switched back largely because of the popular confusion about what "open source" actually is, and also because modern open source advocates have come to think that "open source" means that there's an overt collaboration aspect to it. In my projects, there is not. So it's easier to avoid the mess and just go with copyleft.