Earlier quoted context omitted.
My coworker was a product manager at Netflix and she said in a 2 year period she saw at least 20 engineers get fired. That seems pretty high to me.
Probably depends on team and circumstances. In my ~3 years there I've only seen a handful of engineers I interact with (which was a lot) get fired.
I remember working in a large company with easily a hundred people over the years. I'd say there were only 2 employees that were fireable materials.