Functional Ambivalent has a whole post you should read, but here’s the essence:
If you’re a libertarian and you vote Republican because you like lower taxes, you’re empowering people who would ban books, set up a huge federal broadcast censorship aparatus, give the President the power to arrest and imprison without evidence or appeal, and empower everyone in the medical supply chain to decide who gets treatment based on their own standard of moral worthiness. You’re almost literally selling your freedoms for a few dollars in after-tax income. That’s what you vote for every time you vote Republican.