For Intel's cadence - about 1 backward compatible socket per 2 years, it is much easier to support DDR4. With AMD's cadence of longer attempted support, not so much - DDR4 might look like a joke in 2024.
AMD can't really change their release cadence in the short term. Both from consumer expectations perspective, and the way their teams are divided among people working on next gen vs current gen.
And while greed is everywhere, DDR5 money is not even going to AMD's pockets, so this part is not exactly greed. If you are saying Hynix bribed AMD, I don't see much evidence, it looks like a conspiracy theory.