Why did 8 million people enroll in Obamacare? It isn't because of suppressed demand, as Vox would argue; it's because they had to, as the conservative Heritage Foundation predicted decades ago.

There's a lot of trolling in that first paragraph, so allow me to unpack it. In the early 1990s, as then-President Bill Clinton and other members of his family tried to figure out how to improve and expand health care coverage, the Heritage Foundation developed the idea of the "individual mandate" — the idea, in essence, that making people get coverage would inject money into the system and diffuse risk, allowing a private-sector solution to the problem. That proposal was adopted by Mitt Romney as the governor of Massachusetts, and then made its way into the Affordable Care Act. (Hilariously, the Heritage Foundation tried to deny its role in the idea once Obamacare became a conservative hobbyhorse, but even conservatives wouldn't let them get away with it.)

From Vox.com

As you probably know by now, April 1 was the deadline for avoiding the 2015 tax penalty that results from not being covered in 2014. That's the mandate: you need to have coverage for at least nine months of the year, so if you weren't covered by April, you have to pay up. And so we got the big spike in enrollments in March. You can see it in the graph at right, which is from Vox.com.

At Vox, Sarah Kliff argues that it was demand that drove enrollment. Kliff is unquestionably one of the best reporters on Obamacare in the country, and spent a lot of time talking to the uninsured and pollsters about how and why people signed up when they did. "There's a very simple reason that Obamacare hit 8 million sign-ups," she writes. "Being uninsured is horrible."

People did give it a serious try. And when the site failed them, they waited a few months and gave it another serious try. In March and April, 3.7 million people signed up for coverage, three times as many as the White House had expected.

There's little question that being uninsured can be horrible; a lack of health insurance was the No. 1 cause of bankruptcy in 2013, according to one study. But there's also little question that the individual mandate is why enrollment surged and why Obamacare hit the 8 million mark.

Consider the other data point released on Thursday: that more than a third of those who had signed up for insurance were under the age of 35. This is the famous group dubbed the "young invincibles," the much sought-after group that is expected to pay insurance premiums but rarely require treatment, making the entire system work better for older, sicker, poorer Americans. This is largely not a group that signed up because it worries about the horrors of being uninsured. And it's a group that mostly signed up at the end of the required period simply because they had to.

When the exchanges first opened, older and sicker people, people who had high premiums or who had conditions that had blocked their ability to be covered in the past flocked to enroll. Those people knew the horrors of being uninsured. But at the end of the day, Obamacare hit its numbers because of the Heritage Foundation's idea. It wasn't the only way to insure coverage, but it was the way that passed Congress. And it appears to have worked.