It's a total guesstimate. The interesting thing to me is that I have no idea how anyone else pins down THEIR estimates to any level of accuracy, but they are ap

It's a total guesstimate. The interesting thing to me is that I have no idea how anyone else pins down THEIR estimates to any level of accuracy, but they are apparently confident enough in their estimates to posit things like the "Great Filter", when other (equally likely) estimates such as mine require no such thing.