[jmcatani]

>>> Of course, there could be a macro collapse in 2018 or 2019, which wouldn’t have time to recover by 2020. I think that’s the most likely way for me to lose.

Macro collapse = Bubble Bursting. The performance of YC's personal portfolio is irrelevant to the idea of bubble bursting if there are other investors running a pump and dump on the industry at large.

[etruong42]

I took "macro collapse" to mean some tumultuous event independent of existing market valuations, such as natural (or man-made) disasters, epidemics, war, etc.

I've never heard the term myself, so I am speculating.