How to filter ideas and to go after capital

I'm just following Hacker News for a while now. It happens to me that once in a while I have a product in mind and think it would be great to have. Most of these times 2 or 3 years later the product hits the main stream market. This has happened to me like 30 times now. Am I Avant Garde and am I influenced by signals to my unconsiousness or should I really do something with these ideas and find capital to start a business with these? If so, I'm not into finding capital. How to proceed?