What's Wrong with Banning Internet Gambling?

Aside from the usual economic impact (lost jobs, failed investments, etc.) of upending an established business, what harm could it do?

Ask Nick. He laid it all out quite nicely.

It should also be noted that internet gambling involves a computer and an internet account. Typically, that requires disposable income. I would argue that online gaming "rapes the poor" to a lesser extent than the lottery or Indian casinos.