The reason this makes sense, at least for Github, is because the only valid reason to run your own action runners is compliance. And if you are doing it for compliance, price doesn't really matter. You don't really have a choice.
If you've been running your runners on your own infra for cost reasons, you're not really that interesting to the Github business.
I needed arm64 workers, because x86 would take ~25 minutes to do a build.
Maybe if everything you use is public-cloud-deployed.
Self-hosted runners help bridge the gap with on-prem servers, since you can pop a runner VM inside your infra and give it the connectivity/permissions to do deployments.
This announcement pisses me off, because it's not something related to abuse/recouping cost, since they could impose limits on free plans or whatever.
This will definitely influence me to ensure all builds/deployments are fully bash/powershell scripted without GH Action-specific steps. Actions are a bit of a dumpster fire anyway, so maybe I'll just go back to TeamCity like I used before Actions.
Not just compliance, we run CI against machines that they don’t offer, like those with big GPUs.
Performance and data locality.
You can throw tons of cores and ram locally at problems without any licensing costs.
Your data may be local, makes sense to work with it locally.
Github runners are slow. We're using WarpBuild and they are still cheaper per-minute, even with all the changes Github has made. Then there's the fact that the machines are faster, so we are using fewer minutes.
There are multiple competitors in this space. If you are (or were) paying for Github runners for any reason, you really shouldn't be.