You can work hard and not be stressed. Stress often comes from lack of control, what are the severe dangers?

The most significant danger seems to be you get a low performance review. As a faang engineer that's a pretty weak a significant danger as there are many other jobs that will simply assume you're good.

>Stress often comes from lack of control

Not just lack of control, but lack of a light at the end of the tunnel. A lot of people can tolerate high stress for a while provided they know there's a payoff at the end, an assurance that things are gonna get better.

But when that payoff is taken away or non existent (no money, dead end job, shit living conditions, no chance of home ownership, no having a family, friends group, etc) people can start to fall apart even with low amounts of stress.