"Everyone I know at Amazon is over-worked and stressed out" is the biggest myth. Practically the majority of middle management I knew at AMZN didn't do anything. Source: ex-AWS
There's people that's overworked and stressed out, tho, but those are the minority that do the actual work. I'd say it's an 1 out of 10 ratio at best, being conservative.
This is all because every single project is scoped, designed and implemented with the only goal in mind: your own promotion. Same applies for hires, you don't hire roles, you hire _the structure you need to be promoted_.
Source: same.