At the time of its passage the majority in the US were in favor of Obamacare. Now that it’s in effect it’s even more popular, with large majorities favoring it. So in passing it, Congress was indeed following the “will of the people.” (Of course, maybe your definition of “the people” is narrower than mine: I include all of our citizens regardless of religion or race.)

In contrast, if Congress dismantles the ACA, they will be acting counter to the will of large majorities in the US who want to see the law remain.