Well - Maybe some of them would have considered being able to get their hands on the property of 30% of the population a good thing! (remember the Founding Fathers didn’t get it all right - African Americans were originally counted as about a little more that 1/2 of a citizen, and no women having a federal right to vote until 1920!)
But I think in truth they might see it as an inevitable outcome of the democratic system they had set in motion.
The Founding Fathers were concerned that when a government consisting of a homogenous majority were in control, they would act in a way that would benefit that majority and disregard the rights and welfare of the rest. That’s why they set up the checks and balances they did e.g. the differences between the U.S House and the U.S. Senate, veto power, and designing a representative democracy rather that a direct democracy from the start, to prevent what they called the ‘Tyranny of the Majority.
This phrase was originally used by a French social philosopher, Alex de Tocqueville. It describes the scenario you pose in your question.
This short video discusses if majorities should decide everything. You may find it interesting.