sounds like a crazy number but that comes from amazon itself. i googled it and didn't see any word of a median income, but short of bezos, himself, being on the payroll, i would think it would be impossible for it to just be a handful of top executives making a ton of money.
There's probably not more than a handful of top executives making more than $1,000,000 as it is. you would need $3.75 billion to average $150,000 for 25,000 people