Consider who's setting the tone of the conversation - people with money who want a return on their money. Older folks are not as eager to work for less so they don't make a good investment. Doesn't make them bad businessmen tho. :-)

I think you can found a company at any age. Just go do it. But you're not gonna create a game-changing company if you're past a certain. Old people simply aren't able to see the world correctly anymore. I have yet to see a single person over 30 write anything intelligent about Facebook. I don't really feel bad for you older people. You had your shot - heck, you had the best chance ever with the dotcom boom. Completely talentless individuals were building garbage products and making big bucks. The bar is much higher now than it was back then.