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.
But the thing is, gamblers are now used to gamble with btc and even the market is declining; they are still using it because it is where they are comfortable. I do gambling also and I also use BTC in gambling, the majority of the gamblers are using bitcoin for gambling. For me it is more convenient than to use any alts but the bad side is the fee that can considered as expensive.