Cryptocurrency payment getaways have the lowest transaction fees so that the business owners gets more profit from it. accepting cryptocurrency as a method of payment opens you to more customers internationally. it will helped your business to increase profitability and revenue growth.
I disagree with you that cryptocurrency gateway transaction fees are lower than fiat money. This is your wrong idea but if cryptocurrency is accepted as payment, if its price increases then the businessman will profit but if it is not converted into stable coin or fiat immediately after receiving the payment then if the price of that crypto goes down then the businessman will suffer a lot. Therefore, before accepting cryptocurrency as payment, one should understand these risks and then do so. But accepting cryptocurrency as payment is a smart thing to do in today's modern world