Via Andrew Sprung, here are the final figures for Obamacare enrollment:
Take a look at the bars on the left. These are from the states that run their own exchanges and actually care about getting people enrolled. There was no decline from 2017 to 2018, even among the unsubsidized population.
Now look at the bars on the right. These are from the states that defaulted to the federal exchange, many of which are either indifferent or hostile to Obamacare. All the losses came from those states.
Bottom line: Nothing is perfect, but Obamacare works fine. That is, it works fine if you put in the minimal effort it takes to administer it properly. Conversely, if you don’t care—or, worse, if you actively try to sabotage it—then it will deteriorate. But that’s true of everything, isn’t it?