For Mark's comment, I think an entrepreneur over 30 would tend to ask to "address a market", while those under 20 tend to just build a cool thing and see if any

For Mark's comment, I think an entrepreneur over 30 would tend to ask to "address a market", while those under 20 tend to just build a cool thing and see if anybody is willing to pay for it. The latter is more likely to build revolutionary products because they see market needs that haven't emerged yet. Having said that, older entrepreneurs are more experience and still capable, but perhaps can only build incrementally better products.