The Senate is particulary prone to adopt countermajoritarian preferences because there is antidemocratic, disproportionate representation.
What’s the worst case scenario?
What if the 51 Senators who represented the fewest people all adopted the same position– say a tax on the residents of any state with a population of greater than 5.5 million (the population of Louisiana, the 27th most populous state). (By the way, I know this law would be unconstitutional, but I’m using it as an illustration). Assuming that these 51 Senators from the 26 least populous states adopted the same position, Senators representing 49 million could outvote the Senators representing 241 million.
Majority rule in the worst case scenario is this: the preferences of 49 million people would override the preferences of 241 million.