I also wonder what the official stance would be on, say, bilking the stock market. It seems like standing up for muggle rights would be an unpopular political stance. Since there's no direct victim

Bolded word is redundant. This is a service being provided and nobody is having wealth that they have 'rights' to taken away. This is different in nature to using using time travel or to win at cards or roulette.

The muggles end up better off than they were AND Harry is better off. Almost as though it is a trade.

(Essentially I just agree with Alsadius.)