I wouldn't be against a law that prevented people from gambling large amounts of money unless they could prove the money was theirs. (ETA: whew, a quadruple negative.) The IRS could provide a form that confirmed that someone reported X amount of income, and you should only be allowed to gamble X-Y for some nominal value of Y. This wouldn't be that hard to enforce (the time isn't too significant when you're dealing wi…
I have a huge horse in this fight, because I work for an online casino/slot machine manufacture. The following is my opinion, bl.a I know at least one physical casino where the tax authorities are very happy looking the other way, as patrons gamble tons of dirty cash. They do look very intently on the income and track it carefully because there is a percentage fee on gambling. Presumably that is why people are allowe…
No, because nobody steals $4 million to buy alcohol. Alcoholics don't tend to be spending anywhere near the numbers in OP.
Even if nominal was 0, the proposal would still prevent stealing or borrowed money being gambled. It's not an essential part of the proposal.
If tax authorities are overlooking theft being gambled because they get a cut, then incentives have not been lined up properly. Theft causes a negative externality greater than the thief's gain, so society should not want theft, and if it does then there's a problem.