Provide a tremendous amount of value through the product that will lock one (or both sides) into your platform. Example, credit card merchants provide buyers wi

Provide a tremendous amount of value through the product that will lock one (or both sides) into your platform. Example, credit card merchants provide buyers with fraud protection, improve cash flow, rewards points. Alternately, create a marketplace that is focused on high margin, episodic transactions where customers don't feel the need to dis-intermediate. Airbnb is a good example.