The expectation is for other people (voters) to hear these things, realize that there are some (and can potentially be more) politicians who will do what is in their best interest, and change their voting patterns.
Many people do not believe things can change for the better because they have literally not seen anything in society change for the better in their entire lives.
The last time I saw something actually change for the better in a major way was the legalization of gay marriage. Since then it’s been nothing but manufacturing consent to wars, predatory tax laws that favor the rich, dismantling of protections against monopolies, dismantling of consumer protection laws, stagnant wages, failing to meet or entirely dismissing climate change goals, rolling back reproductive rights 50 years, etc. We’ve recently seen Biden’s Dept of Labor fight back a little bit against the economic stuff, but we’ve been backsliding since Reagan - not that we were really on the up-and-up before. And as for the other stuff, it doesn’t look good.
Voter apathy is a big issue because, even though voting is likely not sufficient for significant societal change, it is necessary for it to occur.