An online casino has none of these. You can operate out of a basement somewhere. No rules, no oversight, no regulation.
You suffer from the misperception that entities opereating outside United States law operate outside all law. This is not the case. Many online casinos are based in England, which regulates them heavily to ensure fair play. The same is true of Antiguan casinos. If the government does not regulate (and therefore certify) the fairness of the casino, there will be significantly diminished revenue as many, many people go elsewhere. This is especially true of internet casinos, which provide absolutely nothing other than gambling; at least in a hypothetical crooked B&M casino, you could eat the buffet or watch the shows or something.
The reason these governments do all this, of course, is that they get to tax the casinos. So your argument that the government doesn't get tax revenue also suffers from the "U.S. government == all government" fallacy.
Even a quasi-legitimate operation that returns 99.99% of all money bet would have incredible payoff to the operator.
You just described how slot machines and almost all table games work in completely legal (i.e., not "quasi-legal") casinos, except that they get to keep more than
The exception to this is games where people compete with each other to capture part or all of a pot which they build by wagering; in that case, the casino takes a commision (e.g., a "rake" or a "vig") and lets the players fight it out among themselves. The casino doesn't care if these games can be influenced by skill; they make no money on who wins the game. The textbook examples of this is poker and prop (e.g., sports) betting.
Assuming you are a voter somewhere, I urge you to educate yourselves on how gambling works before making any votes that might influence or be influenced by it.