Ask HN: Identifying a missed business opportunity

My hope is by asking this question, that many of you who are very proficient in doing a start-up would be able to enlighten some of us who just come to Hacker News to learn from your experience (in addition to the other thought provoking articles that are posted here).

I consider myself a very passionate software developer, despite having (in my opinion) moderate technical ability. I am a father & husband, but continue to seek out time to learn new language features as well as understand emerging technologies and experiment by creating rudimentary examples of what I have learned.

I frequently hear that ideas are cheap, and implementation is difficult. I feel ready to apply myself to start a project, but have difficulty identifying missed opportunities that would likely prove to be profitable. I've stumbled upon a few myself (such as lacking competition in markets like music instrument rental as an example) but struggle to come up with those ideas on my own and have been restless waiting to arrive at an idea that lines up with my personal interests.

Any suggestions?