I highly doubt most people that gamble Bitcoin are going to keep track of their wins/losses.
They dont, that is why they are gamblers. If they did that then the losses would become too evident in front of their eyes.
Not supporting tax evasion but honestly, who is meticulous enough to log each deposit and each withdrawal and then track how much their profits or losses are.
Sports betting, spot traders and similar other risk-reward schemes. They need to keep track of what is happening and how much they are losing vs winning. They come under that group is not that charged up like addicted gamblers but wise enough to assess their situation.
If you cash out your cryptocurrency into fiat, then in that case, paying taxes are easy to calculate and are unavoidable if you do it on an official exchange with KYC. The IRS can't enforce Bitcoin casino deposits with almost all of them being based out of Curacao.
By all means, do pay taxes if you are cashing out or not based on local rules about bitcoin and gambling related income. Also use a wallet in between sending from the casino wallet to exchange wallet because sending directly only increases the risk.