We only have two parties. (Technically, there are some third parties, but they're effectively worse than negligible—voting for them is guaranteed to either do nothing or harm the cause you're interested in, unless the candidate is already a member of a major party and merely cross-endorsed.)

This means that if you care about one thing that one of the two major parties ostensibly supports (or is ostensibly better at than the other), more than any of the things on the other side, you have no choice: you have to vote for that party's candidate.

We also have a mainstream media landscape that is fully captured by the wealthy on the right. It is hard to overstate the extent to which our media carries water for the Republican Party.

And finally, we have absolutely abysmal civics education. It has been steadily gutted over the course of decades. To some extent, this is a deliberate move to make it easier to use the aforementioned media capture to control the average voter.

So if you're a low-information voter, you think the economy is bad, and you want to fix that, you're going to vote for the candidate of the major party that media has been telling you for 50 years is the party that's good at the economy, despite the fact that every time they're in office the debt goes up, regular people's lives get worse, and more protections go out the window.