Or they thought it would be better than their previous place and were stuck once there. Or it was the only place to give them an offer. Or the money was too good to pass up despite the abuse. Or they accepted the abuse for the name brand on their resume.
Maybe they're trying to show off how tough they are. Nobody ever made the mistake of thinking military basic training was an all inclusive vacation. Its plausible.
In an absolute sense it may be a hellish place to work and the average turnover might for the sake of argument be 6 months. But lets say you have a job hopping stain on the resume and you gut out 9 months of amazon, well, that's fifty percent longer than most survive, that employee must have a cast iron stomach and be a focused dedicated team player, etc etc. Paradoxically Amazon being hell on earth is a benefit in that scenario, obviously you don't want to waste your life on HR nonsense, and if you can prove you're tough in 9 months instead of 2 years, well, thats great. Actually, make working conditions worse at Amazon if at all possible so "tough guys" can prove themselves in only two months instead of the made up 9 months.
Well, up until the stories started coming out, Amazon was (and still kind of is) a "big name". So if one of their recruiters comes calling, most people were willing to follow. They'd get their salary and stock golden handcuffs, and by the time they realized the truth, it's too late. You can't leave for a while because of the handcuffs, and what it looks like to leave an employer, especially one like Amazon, within 6 months to a year.