When was the last time a president did something truly great/epoch-making?

[Wounded Bear]

8. For me, it has to be Kennedy...

announcing the Quest to go to the Moon. Nixon's motives for opening up China and the USSR were more profit driven than anything. When they weighed the profits of the MIC against the potential of opening up nearly half the planet's population to American goods, the greater profit won. The MIC hasn't lost many of those arguments since.

The ACA was good, but because it could have been so much better, I can't rank it up there with the New Deal era of Roosevelt.

A close second might be Johnson's Great Society and War on Poverty, which largely worked. But he got bogged down in Vietnam and didn't run for his last term, which if he had he might have further cemented his successes there.

But the Space Program, that was something altruistic, shared by people all over the world, and while much profit was made, it never seemed to be the primary motive behind it. We're still enjoying the benefits of the science and especially the technology developed for that effort.