If you're a customer of an online casino and you are adding funds to your account, don't you want to be presented with payment information that's easy for you to understand? Or course you do - and this goes beyond just having payment pages in your own language. For true transparency, it is important to allow multi-currency transactions, so that your customers know exactly how much they are depositing and withdrawing.
One of the main reasons for cart abandonment is when the customers are faced with an amount of money that they don't understand. For example, if you are a customer from the United Kingdom and you are using a Czech website, you want to transact in pound sterling so that you have full transparency and understanding of the payments you are making. If you are asked to deposit 3000 Czech koruna, this is much more daunting than the same amount in British pounds, which is a little over £100.
Having payment gateways that help you to transact and settle in different currencies will mean that you make payments much easier and understandable for your international customer base. There will be less confusion, and your customers will feel at home on your website - overall, they will feel more confident in parting with their money.