With the market declining, it is not wise to gamble with BTC. Especially the transaction fee in using major crypto such as ETH and BTC. That is why gambling platforms with several alternatives such as XRP, DOGE, TRX and other alts is a good attraction for convenience.
I also do not deposit using Bitcoin although it's popular among the gambling sites, I prefer Doge or XRP if there are options to deposit with these coins it's faster cheap and convenience I once deposited Bitcoin but it took 6 hours to confirmed the transactions and I even use a transaction accelerator to help the transaction.
Normally it does not take 6 hours for the BTC transactions to be confirmed. Most of the transactions are confirmed in 30 mins if you put the recommended tx fee. Most probably you have put the minimal tx fee and that's why it took you 6 hours to confirm. I also use bitcoin too while playing gambling, becasue i transfer one time big amount in gambling site to save tx cost, and keep on playing with that balance.