Also the rate of exchanging coins is too big.
Nobody forces you to use the in-built exchange system.
However, there are several advantages, as it's instant, you avoid both waiting and transaction fees from and to an exchange.
It should be obvious that a gambling site can't compete with rates on dedicated exchange platforms.
The whole system is built in-house without any 3rd party being involved.
Withdraw fees for btc are the same.
"withdraw fees" are bitcoin network fees.
The site uses the 21.co API to determine suggestions, and you can adjust your fees based on your preferences.
If you dislike the fact that bitcoin transactions became more expensive over the last year,
the site offers 8 other coins, including doge with fees as low as 1 doge (72 sat).