Once the recruit makes a paycheck, there is a good possibility that they will reinvest in the opportunity. To build a downline, just find leaders. The purpose of MLM is to build an organization in which many people selling a little bit can be very profitable. If you are interested in huge individual sales commission, network marketing is not for you. You will not always find hard hitting, full-time networkers, and that is perfectly fine.
Many people doing even a little bit of work can produce exponential growth.
Just don't lose sight that this is not the backbone of a successful downline. Each member is important. Also, keep in mind that being a leader is not easily duplicated. Mass mailing Advertisements in magazines and newspaper. All of these are being used every day to gain prospects and recruit new members, as well as to sell product.