I was 38 when I started YC. I think that there are advantages to starting late, well enumerated in the linked blog post. I came to YC from Apple, which is about as stressful a "square job" as you're likely to find, and haven't really encountered anything in startup life that's worse than staring down a Jobs imposed deadline that you Just. Can't. Hit.
The startup I was working for until recently (building scientific hardware) was founded by a couple in their 70's. They basically sunk all of their retirement money into it. I can't say that it was the best financial move in the world, especially when the economy went south and you're trying to sell $1M+ pieces of equipment.
A friend of mine works for a government contractor software shop started by a nana in her later 60s. Except nana was an old-school Fortran programmer and knew her way around Visual Studio. The cuteness wears off within an instant of hearing her speak: she is just another systems architect robbed of all innocence by decades of requirement analysis and systems integration.
I also met another lady in her late 60s at George Mason university. We chatted up at the library checkout line, and I ended up getting lectured about mobile proof carrying code by someone in a christmas sweater, and bifocals left barely hanging on her nose. My 1337 credentials took a hit that day.
Come to think of it, they are in a similar position as the young kids: very little risk. What do they have to lose? They might not need that much money anymore.
I have no numbers in front of me, but I'm sure cost of living for over-65 is greater than for under-25, if only in terms of health care costs.
It's subtly worse than that however: the 22 year old can roll that experience into their resume and make themselves more attractive to future, traditional employers. Talk to any out-of-worker 60 year old, and you'll hear tales of woe about ageism and "too experienced".
