Why did the Founding Fathers create an amendment process for the Constitution? Why did they make the amendment process difficult to achieve?

The Founding Fathers knew that in the upcoming future with the changing time, there would be a need of change in the US government that would stand for the upcoming generations.

Explanation:

The affirmation of Independence had a presumption that people possesses a Right of Revolution. So in order to avoid any riot, they included amendment that offered a method to pursuit the Right of Revolution without any resort to arms and initiated the power in order to change the Constitution to the place it belongs to with the people. The Founding Fathers made the amendment procedure difficult to achieve because to look in the political leads which created the ratification of the constitution. They believed and recognized that the 'ground rules' should be constant in order for a government to function well.