It depends what you've done and what you're going on to do. Spent your time so far as a Java developer, spotted a gap in the market for a tool for Java develope

It depends what you've done and what you're going on to do. Spent your time so far as a Java developer, spotted a gap in the market for a tool for Java developers to do [x], then gone on to build a startup around it? I'm sure there's a fair few of those. And if there aren't it's probably an underserved market, there are plenty of very wealthy companies using Java.