The Affordable Care Act (aka, "Obama-Care") turned the very concept of "insurance" on its head, and "we" have yet to recover.
Insurance carriers make their money by predicting likely losses in groups of insured persons (and things) based on historical data. This is true of all insurance; it is legalized corporate gambling. If you are a 55-year old, obese smoker and want to get "term" life insurance, the insurance company will categorize you with other people with similar risk profiles and calculate the risk of you dying during the term of the policy. They employ actuaries to make those calculations. Same if you have a 17-year-old son to be added to the family car insurance policy. The insurance company analyzes the historical data for thousands of families with Yoot drivers, and calculates the risk that you will file a claim and what it will cost them.
The (un)Affordable Care Act, tells insurers that they may not "discriminate" against people with high-risk profiles. Hell, they cannot discriminate against people with KNOWN ASTRONOMICAL FUTURE COSTS! They must be rolled in with the people who are healthy, low risk clients, thus raising the premiums for everyone. This is why President Obama's "promise" that every family would realize a savings of $2,500 per year in health insurance premiums was a blatant lie.
Health insurers initially were horrified at this mandate, but then the Democrats, with a wink and a nod, assured them that they would be able to adjust their rates to remain profitable, even with these new mandates. The insurers took this to mean that there would essentially be no constraints on how much they could raise their rates, and as a result, changes that might have bankrupted them in a sane world, resulted in massive profits which continue to this day. So it is obvious why O'Care didn't lower health insurance rates, and the Democrats in Congress (it got not a single Republican vote, in either house) knew that most Americans get their health insurance through their employers and would not notice the rate increases as much as if they were paying for their insurance directly. Pity those who must do so.
And why haven't Trump and the Republicans come up with their own version of O'Care? Well, it's simple and it's complicated. First of all, the entirety of the Affordable Care Act is unconstitutional. Congress has no Article I power to get into the health insurance business or to tell that business what it must, and cannot do. Any replacement law would necessarily also be unconstitutional, and the R's have too many "Constitutionalists" in their ranks to get it done.
Just as important, the American people LIKE the part of ACA that guarantees people with expensive "pre-existing conditions" that they can get health insurance, and any Republican replacement law would have to provide for these people with some sort of Federal government backstop - can't expect the insurers to eat those losses - and that would require a "ton" of funding that is not now in the budget. The American public is paying that premium now, not the Feds. Republicans are reluctant to propose a new law that increases the deficit.
The traditional Republican "solution" prior to ACA was to facilitate inter-state competition among insurers (who now operate in each state independently, as required by state laws), give insurers the flexibility to tailor policies to the needs of different groups of policy holders, and push "tort reform," to protect the healthcare industry from astronomical malpractice judgments. But again, that's a State issue and it would be of questionable constitutionality. But I think that train has left the station.
Resolving this now would require a great deal of effort from the Administration and the R's in Congress, and it manifestly COULD NOT BE DONE before the '26 primary season, so "we" are stuck with what we have. If the D's take over Congress it is the end of the world, so this issue - large as it is - would be small potatoes to the Dem whores in Congress.