No, it's how a bad way of forcing a monetisation model onto FOSS works. Breaking promises (cutting 80% of the support term of CentOS 8) is not how FOSS became successful.
I cannot comment on the soundness of the decision, but what was the deal with the community here? I can for example see that Debian is community driven with all the advantages and drawbacks that come with this, but was CentOS ever more than a relabeling of RHEL RPMs in the hopes that people would pay for RHEL eventually? I just don't see why anyone can demand anything (not even promises) from RH here.
CentOS was definitely not started in the hope people would pay for RHEL. It was started as a real community project, taken over mid-run by RedHat.
Ask for your money back.
I don't even use CentOS :P I never liked RedHat from the start, even back in the 90s.