Because people are rarely single issue voters. There are a few here and there, but given the dominance of the US’s two-party system, you often have to make a choice. If I imagine 2 candidates: one who is strongly pro-choice but overtly anti-gay, and another who is strongly pro-life but also pro-LGBTQ issues, that would actually be a pretty tough decision for me.
As much as I want to hate Trump supporters, I can still sympathize with them. A lot are lifelong Republicans who are choosing between someone who will probably try to enact 90% of their personal beliefs but is an authoritarian crazy person, and someone who seems sane but disagrees with them on 90% of issues and will do everything to stymie the things they believe to be right. It’s not a simple choice.
I’m ignoring third-parties here as a caveat, so apologies if that’s the crux of your question. But my opinion is that you should push for and vote for a new system while accepting that the rules are what they are now, and you have to strategize with the current situation.
It’s just an homage to Trump, who is famous for not paying bills!