I work in IT, have for a long time. Employers don't intentionally set out to burn people out, but because IT is a cost center rather than a profit center you get more and more squeezed to do more with less and constantly whittled away at that that's the end result.
Also, most people are terrified to quit not because they fear being fired due to looking around but they are fearful that they won't be able to find other work.
That was the point I was trying to make, but my lovely upper midwestern linguistic style causes me to sometimes only imply conclusions rather than stating them directly. Also your point is very confusing - I THINK you meant "terrified to look for a new job" rather than "terrified to quit" else you would be implying that quitting to find a new job and getting fired and having to find a new job are somehow inequal in real-world terms.