I do not think that companies that were paying RedHat customers all of a sudden starting replacing RHEL with CentOS depriving it of revenue and that's why RedHat decided to end CentOS.
I personally used CentOS for systems that I knew had a long lifetime ahead of them and for their use a distribution that could be "supported" for a number of years was the way to go. But since upgrading from CentOS 7 to CentOS 8 was such a PITA, I started slowly migrating to Ubuntu LTS which makes version upgrades painless.
> I do not think that companies that were paying RedHat customers all of a sudden starting replacing RHEL with CentOS
I think they did. Place I worked had explicit direction to replace RHEL with CentOS to cut licensing costs. Most big companies would pay when they are force to pay and no free alternatives available that'd do the job. They won't pay just because it is nice thing to do.
I personally used CentOS for systems that I knew had a long lifetime ahead of them and for their use a distribution that could be "supported" for a number of years was the way to go. But since upgrading from CentOS 7 to CentOS 8 was such a PITA, I started slowly migrating to Ubuntu LTS which makes version upgrades painless.