Of course the price went down after Obamacare got passed. Can you imagine how much outrage there would have been if it had passed and everyone found out that it was going to cost them double or triple what they used to pay? The government took out some loans (using your future and your children's future taxes as collateral) and made sure they were lower. And then a year or two later when everyone stopped focusing on it and it had gotten normalized they stopped propping it up.
We've been seeing healthcare costs (and premiums, which largely have to match those) go up in pretty much a straight line since at least 1970.
Eg: 90-95% of diabetes cases in the US are Type 2 (Lifestyle related)
I would say it’s because most Americans don’t walk or bike much, food desserts are plenty, transit infrastructure sucks, overworking, and lack of time for vacation/self-care all contribute.
You are forced to have a job if you expect typical medical coverage, and making people do something they don’t want to do won’t incentivize them to take care of their health.
Anecdotally, when the ACA marketplace went live, and I purchased individually, my health insurance costs decreased for a year (no subsidy)