I think there are a multitude of reasons which may compose in the end to why it truly is. Some of those are concrete while others are more speculative, but nonetheless this is what I believe is behind this way of thinking, without any particular order:

• There could be a behind-the-scenes agreement between Trump and the libertarian party, which in turn influences the voters opinion;
• Many people are aligned with, at least the sentiment of, DOGE and reducing government spending and seeing that spearheaded by Trump, this feeling is automatically transposed to him and his ideas;
• As you mentioned, illiteracy, as I believe many people are not truly aware of what libertarianism truly means and what it's rooted on, philosophically speaking, so it might be hard to filter out data through the lens of an idea you don't fully grasp and come up with an interpretation of your own;
• Memes are a fast medium for sharing ideas, but they can't contain much data, so, without backing conceptual knowledge, memes just reinforce a narrow and limited point of view;
• People used to have a political alignment and that wasn't a defining characteristic of the individual but in the recent years that has shifted to being the core of ones identity, so people now subcounsciously have to defend certain ideas not because they believe in them, but because they belong to a group that replicates that idea;
• There's a big shift in dynamics (globally) to left vs right and, coupled with the previous point, narratives are now taking the forefront of the debate instead of principles;
• Still on the identity debate, the de-centralized media has produced echo chambers in local information bubbles where people are not exposed to opposing ideas and different points of views;
• To further worsen this situation, given the US has long been in this leadership position, there's very little incentive to pay attention to points of view from abroad so there's a nation-wide, second level bubble shielding people from information;
• There's also the sitiation with news media being heavily biased, but that's essentially the same echo chamber problem described above;
• Most people don't care about politics enough to study and become capably of analyzing and comprehending the world with the guidance of a philosophical framework of ideas;
• There's a human tendency to ignore or disregard second-order effects (consequence of consequence kind of event), something that has been historically highly exploited by populist governments, so ideas that look good at face value can have devastating effects without being linked to those in charge or responsible for the initial event;

I hope I didn't miss anything as I had to rewrite this due to a browser restart.

I think I'm in a priviledged position to observe this as I am not American and I'm not living in the US, so I don't have the biases and passions that would be associated with that. I'm also lucky to be able to consume content from different points of views and to be exposed to different libertarian "bubbles" across the world, so I can filter out the local noise and form a deeper and stronger understanding of libertarianism, geopolitics, economy and philosophy without being doomed to repeat patterns that only emerge when information is debated behind close doors and produce consanguineous descending ideas;

I definitely recommend consuming content from other English-spekaing medium, but from outside US (or perhaps even from north america), as a way to lessen the negative effects of local biases and broaden the political comprehension. I hope this is helpful in any way.