This is true for the vast majority of states, and the vast majority of people's interests. The political systems in this country have been shaped by -- and frankly, designed by -- by wealthy interests to make the US an oligarchy with various performances of democratic representation.
I’m not sure that’s the reason why it’s only worth campaigning in Georgia, Wisconsin, Arizona and some other states during presidential elections.
Also it is the system that was designed over 100-200 years ago. The problem is the lack of meaningful reform because the people in power are there only because of the current system.
That’s the reason why is it so hard to change electoral system without some external/internal shock. And “unfortunately” US has been way too stable politically during the 20th century compared to most other countries.