on FAANGs, the teams are usually huge, 100+ people doing what a nimbler company does with 3 or less, to the point the employees don't even see that, because the product is now broken into several pieces to give the illusion of complexity. middle managers then break it down further that engineers start being know as the "person that writes the java files in that one directory" and nothing else. This creates constant fear of becoming irrelevant. All while you see 2~10% pay raises while hearing about undergrads making the same you make now with "new tech du jour". This creates even more pressure.
And because this cycle (stagnate, fear, learn, relief) repeats often, engineers start to associate learning a new tech with happiness, just because it offsets the psychological fear for awhile.
