You get a small free option if job change costs are zero. Unvested equity can appreciate. The option is only really free if you can change jobs effortlessly if

You get a small free option if job change costs are zero. Unvested equity can appreciate. The option is only really free if you can change jobs effortlessly if it depreciates, but that's close enough to true if you're motivated enough. Note that this is still catastrophic in terms of diversification. And you can compare job change costs directly to how much paying for this option would cost.