As for what retirees did before ACA.... I chose a job working for the federal government (rather than a much higher paying, vastly more prestigious, and more intellectually stimulating job that I was also offered) because of the benefits offered with the government job. Well, and job security too. Anyway these benefits that came with the federal job included a pension and reasonably priced health insurance that I could eventually carry over into retirement at the same price as when working.
I thought that medical costs were going to go through the roof for demographic reasons, and had predicted that out loud to everyone who would listen to me from the 1970's or 1980's on, over and over until I was blue in the face. Nobody listened but I truly believed it even if everyone else told me I was a total idiot for thinking that, which they did as often as they possibly could.
I still decided to act on the assumption that medical costs were going to skyrocket, whether that assumption turned out to be correct or not, thank goodness. There was no ACA, and federal employment/retirement seemed like the best choice for me under the circumstances.
I worked two years beyond FI, in order to qualify for federal retiree health insurance. Those were two doggone tough years and every day seemed like a century. So when people say, "Oh my, you were so LUCKY to get that health insurance" I am likely to get a strange look on my face.