There is something very seductive about a ramjet engine, it has no moving parts, and all you need to do is pour jet fuel into it: the fuel catches fire and generates a tremendous amount of thrust.
This is the attraction of the two sided market. Just get enough “users” or “prospects” or “buyers” and the sellers will show up and pay you to reach them.
What can get neglected is the need for the ramjet to be moving close to if not above the speed of sound. Otherwise the fuel does not catch fire, it just dribbles out the end.
Two sided markets are the same way, when at least one side of the market achieves critical mass then both sides can start growing profitably and it’s a wonderful thing. But too many times you are below critical mass and do not have the money to acquire enough users/customers to get your startup to reach a critical mass for take-off.