Many gambling websites now offer many cryptocurrencies to use on their platform. To have lesser fees I often use TRX or doge to play, the amount you will earn is still the same if you convert it to stablecoins. It also has an advantage using those because you can play longer with those cheap coins. Even if the fees are low, using bitcoin or ethereum to gamble is not good for me because you are just wasting a big amount money in the future. This is what I've realized wasting more than 0.01btc just to gamble in the past.
If you have TRX or DOGE already in your wallet, then there is nothing wrong in using them for making the payment. On my part, I mostly go with BTC, since I don't have a lot many altcoins with me. Purchasing altcoins using BTC and then using them for the payment can be counterproductive, due to the extremely unstable exchange rates. And I don't necessarily agree with the last part of your post. The payment needs to be made and it doesn't really matter whether you are using BTC or fiat for that. If you really feel that you will lose out in the future, then why can't you purchase a large amount of BTC right now, rather than worrying about spending these small amounts?