The 5% fee isn't fixed, it says they may charge up to 5%. And they only charge fee for withdrawals as you can see ‘Pmalek’ described above. Their terms and conditions page says,
7.1.9. We reserve the right to apply a handling charge of up to 5% on deposits and withdrawals to cover transaction costs.
I have asked their support to make it clear and mentioned about the fee details of T&C page. Support have given me the actual fee chart but said nothing about the 5% fee. Though he added that his given withdrawal fee chart is correct
The network transaction fee is 0.0005424 BTC for Bitcoin, 0.0004 ETH for Etherium, 10 USDT / USDC for Tether, 0.002 PAXG and 0.00000226 BCH for Bitcoincash withdrawals.
BTW, It's great that Cloudbet have added those classic games finally. Seems like we can place two different bets before every plane launch in aviator game. Personally I like this option much. Maybe the free play function doesn't working yet? Dice game have 3% house edge. Compared to other casino it seems high enough. Do you have any plan to lower it in future?