Arguably, human nature hasn't changed much in thousands of years. But there has been plenty of change in human culture/nurture on a much smaller timescale. E.g., look at a graph of world literacy rates since 1800. A lot of human culture is an attempt to productively subvert or attenuate the worse parts of human nature.

Now, maybe the changes in this case would need to happen even quicker than that, and as you point out there's a history of bad attempts to change cultures abruptly. But it's nowhere near correct to say that the difficulty is equal.