I'm an H1B. I get way, way more than a living wage (I can basically comfortably support myself and my partner - a citizen, by the way - rent a large condo in a nice and expensive neighborhood, pay all bills, and still set aside a nice pile of cash for my savings account every month. I can assure you that I don't consume less than an average American (or even an average American in a similar job). I've also got significant raises every year since I came to the States.
It would seem to me that if an American would be willing and able to do this job, the company that hired me wouldn't have to pay me anywhere near as much (don't forget that they also paid the bill for my relocation - from another continent, no less - paid for my H1B, and are now paying for my green card process).
So, whose job am I "stealing", again?