They make sure enterprises can run Linux that doesn’t “suddenly” (read: with less than 2-3 years notice) break their critical workflows because some component loses support or some dependency reaches EOL - they do this by extended maintenance, backporting (security) patches to old versions, providing tailored support etc.

This is very valuable to enterprises and so they pay a lot for it.

For example, you can still run Red Hat 6 safely and securely until 2024; by that point Red Hat 8 will have been out for 5 years already.

Red Hat is the premier organization doing open source development. They optimize the experiences for enterprises: lots of support and a goal of helping it be easy to use so enterprises can focus on their business logic.

Lots of well-hated projects come from Red Hat: systemd, wayland, ... but they have also contributed well to some other projects which are much less controversial.

Services/products of a company usually bring one of the following to customers: 1) improve revenue, 2) lower costs or 3) manage risks. RedHat is probably mostly about the last one, manage the risks of running linux.