In Capital and Ideology, Piketty does a review of modern democracies, there's a two party system of left and right in every one except Poland where there was at the time of writing a far right and right wing party competing for dominance. Conservative parties typically rely on rural voting bloc, less educated and much older people, it's almost universal somehow, that doesn't make their opinion wrong off the bat, it's just demographics of voting. There's also actually a component of "harming these people I disagree with" that drives the vote for reactionary groups and is an active part of Murdoch sponsored media, there's not really a thoughtful process about how it could harm themselves.
For example, there was the irony of multiple cases of people voting for Trump because immigrants are bad, and then having their spouse deported for some visa violation. Or one can look at the people who have opposition to abortion voting for Republicans. Then someone who cannot consent is raped or someone has a non viable pregnancy and neither is eligible for an abortion, which has happened since Roe v Wade was re decided. In the USA, the Senate is decidedly unrepresentative of the people of the United States as a whole, the House less so with the limit to 435 members, but not as bad in some ways.
You can also look to Brexit post vote interviews where people who voted in favor of it said they didn't care if it hurt the UK, they wanted it to happen.
An older example in the USA, the Reagan administration characterized AIDs as the "gay plague" and played down the effects and had no official response to the health crisis other than to joke about it, delaying an effective national strategy. Today there is still a gay faction of the the GOP called the Log Cabin Republicans that is barred from some party events but still back the GOP, Peter Thiel has become a big GOP backer in spite of most state party platforms calling gay people abnormal and most subsequent federal GOP administrations sending and supporting people in Africa to criminalize gay sex.