Quitting before promotion

My cousin works at Amazon. She puts in 60+ hours a week. She does this in FOUR days on average. She's an area manager at an Amazon warehouse. She graduated with an industrial operations engineering degree and makes a good living there, especially b/c of the stock going up (which is the only thing that makes the crazy hours not add up to minimum wage). 

She told me that she's up for a promotion soon, but she probably won't stay that long. The costs of working there greatly outweigh the pay or any other benefits. 

Most importantly, her schedule is completely unpredictable based on her bosses random whims. She is constantly changed from night to day shift and there doesn't seem to be any good reason for it. She ends up with about 4 hours of sleep between her shifts. I can't imagine what kind of toll those long hours and constant pressure is taking on her health. 

She started this job with so much enthusiasm. She's now desperately looking for another job and can't wait to leave. It's only been ONE YEAR. Yes, they're offering more stock with her promotion, but it's just not worth it. Amazon has taught her the valuable lesson that money isn't everything but it wasn't through their good intentions. It was through their horrendous treatment of her and every other employee there.