It shouldn't be to make lots of money! This isn't the stock market. Startups are much riskier and more likely to fail.  Greed is a wrong reason to invest.

Of course, if you invest wisely, you can make money.  Our advice?  Invest only in what you understand (and preferably love). If you are a customer and love the product, it’s likely a good investment. If you don’t understand it, investing may be a bad idea. 

Investing should not be solely about earning a return. To invest in something as risky as a startup, you should feel something extra beyond just the business model.  For us, that “something extra” is the fulfillment we feel helping a founder take "their shot" at making our world slightly better. We also think it’s pretty cool to learn about different industries when we get updates from the founder.