This phenomenon is a close cousin of the sunk-cost fallacy but it's not quite the same thing. I'm talking about rationally assessing that the value of an asset

This phenomenon is a close cousin of the sunk-cost fallacy but it's not quite the same thing. I'm talking about rationally assessing that the value of an asset has fallen, vs. sunk cost's "we've come this far..." - even if you're rational, it can be hard to sell and psychologically tolerate taking such a huge loss.