If the gambling sites depend on the value of the cryptocurrency then, it has a big impact on gamblers. But, I think that gambling sites use cryptocurrency which is not converted to USD since we all know that market is very volatile it can go up and down.
I think that much more on the personality. Remember that some gamblers used USD of fiat money to bet but others may used crypto to bet in the betting platform. You can't deny the fact that if gamblers itself who will be determining which value that will be used to gamble whether it will peg with fiar or crypto. In this case the site can't be blamed once crypto gamblers loosing their money