Liquidity providers make money based on the spread... right now a liquidity provider would have little competition and could make a lot of money. Because bitshares is decentralized, more liquidity will flow into the system easily and will degrade the profitability of the early liquidity providers.
So, get in now and make a bunch of money while simultaneously using the referral system to leverage the traders that you bring into the system as your profitability from market making decreases.