I think unlike in the usa, in Nepal price doesn't go down immediately. It slowly goes down as buyers are scarce. In Kathmandu in particular, since most of the landowners are rich, they just tend to hold the land even if it is irrational of them to do so. So, it is those people in margin (those in loans, in need of sending kids to foreign countries for study, to pay back previous loans, loss of business, loss in dalali etc and willing to change business) who begin to sell  land first, and once the price goes down steadily, some others too join.