Define "budding system that was working". Before the ACA, the number of uninsured Americans was around 50 million and insurance companies routinely denied coverage or charge higher premiums based on pre-existing health conditions. ACA is not perfect (due in no small part to the concessions that had to be made in congress to get enough votes) but i'd say it's been a net win.

Going back to a pre-ACA system won't lower premiums that much. Medical costs have risen in the last decade, same as any other goods or services, and the way US healthcare is structured, with hospital and doctors negotiating with a profit driven middleman (insurance companies) makes it almost impossible to change the rising premiums.

US healthcare will continue to be a mess until there's a universal healthcare system or single payer system similar to any other developed country on earth.