The chart is in fact for the year of founding, not sale. For 2013 it would be companies founded and sold in the same year, and I would expect that to be rare.
I dont think that is true, YC seems to be progressively accepting later and later companies. the 2005 batch was a bunch of kids in college. 2013 is seasoned engineers working on it for a year already with massive traction.
I think what's expanding is the standard deviation/variance. The mode is not moving all that much. Mean/median, a bit. There is definitely a trend toward some later companies (it used to be ~none), but there are still a lot of early stage.
I am sure this is true, but very specifically getting to just the level of above 40m, it can't hurt, can it? I am not saying if you fund them later they will become dropbox, just have a higher likelihood of hitting 40-50m
Dropbox is an ironic example, because Drew applied right before the deadline with a video, a string-and-wires prototype, and no cofounder. He'd been working on it 3 months and had just barely quit his day job.
This is the first batch where I knew people in YC. They started their company (with an entirely different idea) on Feb. 1. The founders were all between 24 and 26 at founding, all 4, 2010 or 2011 graduates. Reddit was started after Alex and Steve graduated from UVA. DropBox (S07) was Drew's 4th startup.