certainly there is an already created altcoin only for crypto gambling.
bitcoin is the spirit of crypto, its function is inappropriate for gambling.
BTC is actually more appropriate in gambling. Its sort of a chip in casino.
When a gambler holds chip, in their mind its just a chip and psychologically they tend to bet more using these chips for its doesn't look like money and will just gamble it away which what casinos want. BTC acts the same way which btc casinos wants BTC gambler to spend it all.
It's a cheap that is not for gambling purposes only and its accepted widely in the crypto world.
It's quite different in gambling tokens where you can only exchange it in the site or exchange in certain exchanges, that's why people choose BTC over others because of its big liquidity and they will not worry a lot since its more stable than other type of coins, including gambling tokens.