If you buy and hold Bitcoin for investment, of course, you wouldn't deposit it into a casino to gamble. But if you have Bitcoin for transactions like you would with money, I don't think it's a problem to deposit Bitcoin for gambling. I also gambled with Bitcoin in the past. But now I use stable assets like USDT. Bitcoin is becoming increasingly valuable, so collecting it for the long term isn't wrong. Casinos accept deposits in other ways, so we can still have fun without losing Bitcoin.
They're gambling lovers, even though they hold bitcoin for investment provided is not kind of holding that you don't have access to withdraw or transfer from the wallet to another wallet, I think the person can use it to fund its casino account if the person wishes to credit its casino account with bitcoin
In other ways round you're right, because anyone can fund casino account with other cryptocurrencies, some gambling website have different coins they accept to funds their wallet for casino, but the thing is that almost all the casinos have a similar requirements to fund their wallet.