That's because CentOS didn't meaningfully cut into their major business which is support. Anyone running CentOS outside of a lab setting understood they were on

That's because CentOS didn't meaningfully cut into their major business which is support. Anyone running CentOS outside of a lab setting understood they were on the hook for their own support. Most CentOS users were never going to be paying RHEL customers. You can't lose what you didn't have to begin with. Along came Oracle which is taking big customers and literal bags of money away from RH's core business by reselling a warmed over version of their own product at a lower cost.