[bluGill]

The problem is we don't really know. Drugs that are almost out will probably still come out. However we are most likely to lose ones that are in the here are 100 things we could try at high cost - we know from experience than 1 in 1000 of these ideas is useful. If the cost recovery is high enough you try all 100 ideas to see if they lead anywhere, and then find another list of 100... If cost recovery isn't high enough you don't try any, and we don't really know what we lost because we don't know which of the ideas before actually will turn out to work.