I think the reason the largest startups focus on institutional investors is because these are by far the largest users of financial data and are willing to pay for it (just look at Bloomberg's subscription fees). With just a few customers, you could have a million dollar business. How much would an individual pay for access to similar data? Given they could just give their funds to a professional to manage, probably less than that professional costs them.

That said, your startup looks cool and could be very useful if you're able to extract data all historical financial data from annual and quarterly filings (something that is very difficult right now) but it's worth noting that there any many startups in the space of making investing easier for retail investors (many of whom frankly aren't passionate about or interested in anything to do with investing beyond growing their personal funds) probably the most notable ones are maybe Wealthfront https://www.wealthfront.com/, Robinhood https://www.robinhood.com/, and most related to your startup, Quandl.