What can older inventors offer you? A product, often a patent, and access to cash you simply don't have.
It's important for an invention to be fully developed prior to introduction. Many novice inventors make the mistake of rushing a product to market before it's ready. More experienced inventors are willing to spend a year or two fine-tuning the invention so it's as marketable as possible when it hits the market.
Experienced inventors are also more likely to have access to funding. Their friends have more money, and they often have a network of business associates who want to fund the product. One inventor I worked with who had an engineering background raised $150,000 from his engineering friends--$5,000 at a time--to market a pump he had invented. He never quit his day job--he had a friend market the invention for him instead.