Some will say that they have gained sales from having a Credit Card capability. Others will say that a CC is required if you are going to sell anything, anywhere, and especially on the Internet. I have been both ways, and have chosen to not use Credit Cards. Others may have different experience with them.
One of the problems that I had with the CC were the fees and the minimum that was collected every month. The minimums vary, but it will be at least something around $40 a month for an on-line account, double that for the option of using a CC at point of sale with telephone verification, and many services are a lot higher than that.
Then there is my Internet sales experience. I have been selling videos via the Internet, and thought that would be a good incentive to get into accepting the CC payment option. However, buyers were preferring to use PayPal by about 10 to 1. PayPal takes a % of sales with no monthly minimum. There were months when the CC sales weren't sufficient to cover the minimum fees from the CC provider, so dropping the CC service was an easy choice.
My experience with doing Craft Shows and other sales without Credit Cards has been a good one for me. The lost sales for not taking a CC have been insignificant, so few in number that I can't recall ever regretting not being able to take a CC. I take personal checks, and have only had one (1) check bounce, for $150, in ten (10) years. It seemed like a lot at the time, but it was only a couple months worth of the minimum fees from a CC provider.