Anecdotally I've seen it get a lot more common to use third-party managed runners (e.g. Blacksmith) for anyone that needs slightly beefier machines and/or a caching system that actually works.

Yeah, we migrated to self hosted actions runnrers on hetzner 2 years ago, the speed improvement was massive

GitHub charges too much for hosted runners. It's pretty straightforward to switch to another runner provider at literally half the cost of GitHub.

They are not just more expensive, they are also slower. Last time I compared them, AWS ARM64 instances could easily run jobs 30% faster, for the same CPU/memory count, than those that GitHub offers.