"Even if he starts with the absolute minimum bet, he could still run out of money after losing thirty, fifty, a hundred times or more in a row. "
If the site you're gambling at gives you a 30 loss streak in less than 1 million rolls it is rigged.
*facepalm* It is irrelevant the size of the losing streak - it does not prove that a casino is rigged, only that variance thus far has been a huge dick to you. To prove something is rigged you actually need to find a piece of code that is changing the outcome of your rolls such that you lose, until then the best you can say is that the site is extremely suspicious.