Author of the OP here - to put some more empirical backing to this, virtually every single engineer in our candidate pool values illiquid equity at 20% or less of face value, and about one in three give it no weight at all.

Totally off the topic of the thread, but it's why I do things differently with the people who work for me. I'm the sole owner of Otherbranch, but I pay out a percentage of profits over certain thresholds (between 25 and 75%, rising at higher levels of profit) to the team. Keeps things concrete and aligns incentives with building something that works today rather than obsessing over a hypothetical exit.