I want to quote from Kris Abdelmessih, who directly inspired the PayPal case:
Competitive equilibrium will mean that the casinos who can bid the highest for the “customer” is the house that can:
a) source the most uncorrelated offsets to the wager
and
b) has the biggest bankroll
In the trading business, condition A is satisfied by the market makers with the best data/analytics and “see the most flow”. A firm entrenched in both equity markets and futures markets with licenses from both the SEC and CFTC is going to be more efficient at laying off the risks it acquires from serving tourists regardless of the venue they choose to play in.
A and B will create a virtuous loop. The best players will build larger bankrolls which allow them to outbid competitors further which earns them first look at the flow which improves their models and so forth.
From: Why You Don't Get Paid For Diversifiable Risks - Party at the Moontower
In certain markets, scale players benefit from increased flow and throughput, and slowly poison the market for all the other non-scale players.