> Jokes aside, how do you end up having more than 500 excess people than what you need?

There never is an excess amount of workers (sure, there probably are 4-5 exceptions). What happens is that they need those employees, but instead are going to demand that the employees that are left pick up the slack. Which they will because they need a roof over their head.

Those companies are merely cutting costs, they don't actually have any excess employee.