Yeah it is quite high, and the network could easily be changed as well, there is no need for it to be on ERC20, you could move it to bsc, or trx and you could get it quite easy and cheap.
There are some other networks as well but not many people use it, so the smartest one would probably be going with BSC, because that is basically easiest way to get the same exact address, what you send to ERC20, you could send to BSC as well on the very same address and get rid of all the possible complications. Stake is so huge that they could handle this in a single day if they wanted to, but I am not sure if they would care about people who can't pay a 10 fee like us.
Stake is indeed of the biggest casinos with a lot of high rollers but the majority will still be small gamblers who will think that a 10$ fee is too much. Guess we need to wait and see how popular USDT becomes and hopefully they still condider adding alternative networks besides ERC20.