Regardless of how fantastic your idea is, the fact remains that there are millions of people out there with what they believe are fantastic ideas -- most of which aren't. For someone to distinguish between fantastic and non-fantastic ideas takes a significant investment in time, and no sane person is going to make that investment given the negligible odds of a payoff.
Or, put into economist-talk: The friction of investment discovery is too high.
This presupposes, of course, that you don't have any special advantages which will lead an investor to think that your idea is more likely than average to be a good one. If Jeff Bezos says "hey, I have a great idea for a business", people will listen -- but most of us don't have that sort of credibility.
As a student there are other reasons to code it up besides just concept of selling it. You probably already know this but, just in case, I thought I'd throw that out there.