His argument is that the rich people gambling do not have to pack a lot of odds as in parlay bet to accumulate a high odd size that will give a satisfying potential win. The rich has the money to risk huge amount to a single game for instance 2 odds staked with $1 million to win $2 millions, but the poor staking with $100 to win $2 million has to pick multiple legs to accumulate odds to get such potential win. It hence decreases the gambling winning chance whilst the rich gambler chance remains increased.
Well, this is quite logic. Gambling is a matter of how much you are able to spend which can reduce the chance of loss. Betting with $1m to gain x2 which is $2m is a great deal and high chance to succeed, while betting $1000 to reach $2m is quite impossible.
The problem in this approach is what we see in the gambling scene is that the great majority of users are not the rich people but those poor and middle class. Companies in gambling can tell their great part of benefit come from those called poor as the whales represent a small percentage from total user base.