If you think you can get away with it without getting caught red handed by casinos and bookies, sure, you can make some money out of it, no doubt.
But you also would need to consider anyone wishing to perform arbitrage would require a quite large initial bankroll and deposit it on different bookies in order to start arbitraging, the risk would not be worth it, considering your balance could be confiscated by those bookies at any time.
If you want to arbitrage and have less of a risk to lose all your money, it would better just to stick to perform arbitrage between cryptocurrency exchanges, instead of casinos. It is not against their terms of service and if exchanges are trustworthy, you would not lose your sleep thinking how much you got deposited on those.