The investment is not risky, the risk is all on the investor, Especially in this case.

But statistically speaking, investing in a pre-revenue startup is extraordinarily risky.

Of course that wouldn't work for me, but it does seems a less risky approach if you can set it up like that. 

The more experienced and proven your business model is, detailed business plan, and a certified financial history to back it all up, the less risky you are to lend to and easier to finance you at a lower rate....

Inheriting a tenant on your first deal is a little bit risky. 

If learning is what your after, it’s a no lose proposition.

Investing out of state can be very risky as you are often not able to see, touch, and walk through your investments. 

@Vipul Shah just don't use credit cards for this purpose, if you are doing so, it likely indicates that you are not well capitalized, and it is very risky.

Otherwise their risk is that you could simply walk away from the deal. 

A duplex would cash flow better.You're right though, the cash flow would definitely be better from a duplex and most likely less risky.