How do you grow rentals quickly?

[Philip Marzen]

I read a lot about people that go from one property to 10 in just a year, for example. How do they do that with rentals? I assume that they must be getting awesome deals where they bought very low, did a quick rehab, and then refinanced and had a ton of equity and then used a home equity mortgage. If they used all their initial money to buy the place then they are back at zero, have very little equity in the property, and are only cash flowing a few hundred a month, that's not enough to go buy another property in just a few months. Is there something I'm missing? Is there more to it than just an incredible deal?