To succeed in social, you need to exploit network effects to scale your user base. You might get a flash in the pan with some seeded content or go viral for a brief second. In the long run, you need to spend big and more than established competition even in niche markets if you want to create a beachhead. Even if you had the capital to do it yourself, you probably shouldn't since that's not smart in terms of risk. So then you will need to resort to investment from VCs (even angels can't fund a social product beyond seed). At that point, you have conflated your purpose from a do good-social enterprise to a venture that needs to provide 50x return for your investors.

Remember the value per user that acquiring companies pay for when they acquire said company and compare that to how much you will need to spend to acquire them from scratch. If you can't nail the distribution (sales & marketing) side of the equation, the product won't have a chance to get off the ground let alone survive.