Many people join Forsage and do not refer anyone and still make some earnings, sometimes quite substantial. This can be achieved due to something called Spillover, or often referred to as Overflow within Forsage. This activity is taken care of within the X4 part of the platform. Spillover can be affected by various factors, but much depends on how active your team around you is that you join.
Also your earnings potential with spillover, when you actually achieve it, can be increased if you fund the higher slots in X4. For example, if you only join at the minimum 0.055 ETH and just fund your slot 1, this will only pay you a small amount of ETH when you cycle. Whereas the amount of ETH you will receive when you cycle at for example, slot 3 or 4 will be much higher.
Please beware of some people promising you quick earnings. There are never any guarantees and spillover may take quite a while to happen. However, remember that Forsage is a long term project and once you have funded your X4 at your desired level, it may help you to think of this as a low cost, low risk, long term investment.
This video gives a more detailed look at how Spillover works in Forsage