I guess 1% should be the minimum amount you can earn.. and you are right, that requires big money. Bet $1000 usd, and you'll get 10 usd, I think that is not enough... maybe $10,000 and you'll get $100 the minimum, could already compensate your effort in finding artbitrage betting opportunity.
And now you are touching one of the greatest problems with arbitrating not only when it comes to gambling but also when it comes to trading, people look at that way of betting and they think they can make a fortune because after all they could avoid losing a bet for their entire career, however the profits that they are going to get out of those bets are so low that the capital that you need in order to make any kind of significant profits is very high, and if you try to make those bets with cryptocurrencies you only need to get scammed once for you to lose so much money that it will be impossible for you to recover from such loss.