"We bought 100 properties without using any of our own money"

[Nat C.]

This statement is something I keep seeing again and again on the Bigger Pockets blogs;

people saying they flipped 100 properties using someone else's money.

They proclaim they had one of their investors pay for the purchase and renovation and they apparently have a deep pool of investors ready to throw hundreds of thousands of dollars at each deal. The blog theme is always tutorial, with the message that anyone can do this.

The unanswered question is, where are all these cashed up investors and why are they willing to hand over these large amounts for a non-guaranteed return?