IMHO Having more time like 5 years doesn't mean anyone is going o build something more valuable; I even think by having a limited time to deliver something (e.g 6 months) you are going to deliver the most valuable thing and skip anything that is simply not needed for user.
So I think you should stop thinking about the time limit as a constrain to deliver a GREAT idea.
It might be more valuable simply by virtue of not being a product of this mindset. Certainly nobody on HN is going to tackle a problem that might take five years to bring to market, even as we adore products that obviously took more than six months to produce (the iPhone, the Roadster, etc.)
While I'm giving out free advice I have no intention of acting on, consider tackling a problem with a significant initial investment in personnel. Nobody on HN is interested in launching a startup with a bunch of employees. If you find a niche where you would need that you can expect not to have much competition from folks around here.
