I'll sell one for half that

You're not wrong

I assume that stock was in the form of restricted stock units that vest over the course of a few years. I've seen this kind of thing play out at a few big tech companies over the years and have seen people lose literally hundreds of thousands of dollars in delayed payout.

They offer these as a "loyalty incentive" so the employee wants to stay while of course offering no loyalty in return when they decide to execute layoffs.