In my life I have had precisely 3 opportunities to realistically pay for a Linux distro:
- A boxed copy of Mandrake (found on the shelf at Sam's Club many years ago) that got me into it in the first place. I talked my mom into that one.
- Professionally, evaluating whether the support and customer service provided by Red Hat was worth using it over CentOS. My recommendation was no, and as it turns out since we did not run software that required it, we never encountered a problem that having their assistance would have solved.
- Semi-professionally, really wanting to throw some money to the Proxmox team for access to the enterprise repos and support ticketing on my home-lab-ish cluster, and not being able to afford it because they insist on annual billing.
So no, sometimes it's as simple as the combination of price/features/support not being competitive with the free alternatives.