You're speaking to a guy who went from 255 to 195 in less than 6 months (after 3 years I'm at 210-215). I did it through hard work. See diet and exercise forum for more details.
No, it's creating winners. If the greatest determinant of wealth in North America is the wealth of ones parents, then I'd be working 7 days a week in a bakery at minimum wage. Just out of curiosity, do you come from a wealthy family since you obviously would fall in the top 1-2% of income as a doctor?
If people would put as much effort to better their lives and sacrifice as immigrants do, then you'd see much less people on lower incomes. Middle class usually creates complacency.