It's also not that Red Hat saw something wrong with CentOS Linux. To put it simply, between 2014 and 2019 Red Hat learnt that the company needed a free RHEL upstream more than they needed a free RHEL downstream.
And a lot of effort went towards making it possible to ship RHEL's upstream as a rolling release. Consider that ten years ago you had to ask specifically, months in advance, about updating a package in a RHEL minor release. In 2010, a quality engineer and I spent a few weeks working on grep just to make sure that the bugs were fixed in Fedora before RHEL 6 forked, because otherwise we'd be stuck with the bugs for years. These days I could just open a merge request on CentOS Stream and ask to update to a newer version of grep.
I may be off, but hey. As I understood it at the time, the reason wasn’t “OMG there are folks not paying us for the bits” but rather “we have this number of engineers, they can work either on CentOS Linux or on Stream” and Stream is more of a benefit to Red Hat as an upstream for RHEL.