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.
Indeed correct, but for me, as long as you are buying BTC at rates acceptable and you will win BTC higher than how much you've risked, I think it is acceptable to still use BTC for betting. Unless, BTC transaction fee is too high that it affects the frequency of your bets. But it is not always the case, most of the time, crypto gambling sites will allow you to decide how much you want to bet in order to play decent amount of games and win decent depending on the amount you've bet.
IMO, to play efficiently, we could try to use altcoins that we are not actually using for usual transactions, those that the purpose are merely for gambling, because like trading, some gambling site have their own crypto to use and it provides perks and discounts.