I don't remember having an epiphany; it was sort of a gradual process. I guess the closest thing to a "moment of conversion" was installing and using Ubuntu, and soon realizing I no longer had to be abused by Windows. That was around 2010.
These days, I am much less fanatical than I used to be about free software. I still want to release any code I have control over as free software (probably AGPL to maximize freedom for downstream users), but I don't refuse to use non-free software. I am on Ubuntu right now (after more than a year of insisting Debian was better for me), but may end up buying a Mac so I can build and distribute apps for iOS.
Some reasons for my loss of zeal:
1) No modern devices can run on 100% free, de-blobbed software all the way down to the BIOS, like the FSF insists we all should be using. What happens when the supply of old Thinkpads is depleted? Will the FSF's annual ethical giving guides continue to push people to buy them for themselves and their loved ones?
2) Sometimes for work or school I need to use Slack, Zoom, or Keynote. Yes, there are free alternatives, but my colleagues or professors are not going to go out of their way to accommodate my refusal to use non-free software. I'm not as popular as RMS is, and probably never will be.
3) I'm a developer, not a sysadmin!
