You have to decide what your goals are, and make decisions on how you spend your time based on those goals.
If you really would like to be an entrepreneur, recognize that a successful business cannot, in most cases, be built in a few hours of spare time here and there. Suppose you find an "investor" -- then what? By definition, an investor would invest capital in your business, but how is the investor going to see a return on that investment?
Perhaps what you are actually looking for is a co-founder. You seem to have the technical side of things covered, but have no interest in the business side. However, you also say you have no time for this project, so is it reasonable to assume that you will find somebody willing to take the website and turn it into a functioning business on their own?
If you are, as you say, satisfied with your job and career, then what was the purpose of building this site, if not to turn it into a functioning business? Maybe you just enjoy development? There are plenty of people like that out there who make plenty of cool things as side projects, and do it not-for-profit. These bits of code can be contributed as open-source projects, or blogged about, and so on. Occasionally, one of these projects is cool enough to get some traction, and at that point, maybe there is a business opportunity there -- or maybe not.
And finally, if your goal is simply to build something and flip it for a bit of money, then your best bet is to try and find a buyer for your site. But that's what it will be: a buyer, not an investor. It's unlikely that you'll find somebody willing to pay you for your work, but also allow you to retain any ownership in it. It's also very unlikely that you'll receive a large sum of money for a site with no users, even if it is a "great idea."
Again, it depends on your goals:
- Do you want to found and run your own business?
- Or do you enjoy your career and plan to stay employed for as long as you can?
- Are you willing to put an extraordinary amount of time into cultivating something that is far from guaranteed?
- Or do you want to build something cool and then hand it off to somebody else?
Remember, there's no shame in being a creator rather than an entrepreneur. In the end, your most limited resource will be time, and you should make sure you're spending it in whichever way will make you happiest.