Well, considering we pay the most for health care of all industrial nations and don't even crack the top 10 for best health care, I don't think it can do any worse.
I've seen the insurance companies time and time again deny coverage, make the system so convoluted that people just give up trying to get rightful coverage and pay themselves, make the stress on friends, family and injured/sick patients absolutely horrific, kick back claims again and again just to avoid payment when they were perfectly correct to begin with, demand doctors see more and more patients with less and less time actually spent on them and it goes on and on.
For profit insurance has every incentive in the world to deny you care - it's more money in their pockets and bigger bonuses for them while hundreds of thousands of Americans go bankrupt over medical costs.