Why people lie about political beliefs?

Because leftists get mad as fuck.

A large part of the issue pertains to a less than summary knowledge of the ideology and/or group with which one identifies, and the modern conundrum of "hearing with the eyes and thinking with the emotions", or what public education and media foster as sensational thinking utterly bereft of critical thought and analysis.
Our overall body of knowledge in the public or corporeal sphere has greatly slowed its forward momentum largely due to our seeming modern ability to recite what we assume are the right answers, but our seemingly inborn inability to know how to actually seek such answers out or test the very means by which we arrive at such answers and sift, not only the real from the fake or the true from the false, but also, more importantly how we divide the true from the almost true.
Even a statement that is 99% true is a lie in the most basic and fundamental of senses. Knowing the full scope of such a difference in reference to the intrinsic and apparent applicable value(s) and terms is what truly separates knowledge from wisdom.
We have neither gotten smarter nor dumber in the procession of former ages to the present one; we have simply ceased from revering the accumulation of knowledge and truth as valuable elements taking them now more for granted than before, and elevating the unimportant, ephemeral, and peripheral details of ever changing definition and reference to be of greater value and worth than they can, by even the crudest definition, even loosely be mistaken or hoped to possess.
Politics, like logic, is merely the ceremonious and pretentious practice of attempting to formalize how the question is settled as to who shall control and how they shall make attempt to control a/the discussion in the public sphere in whatever capacity is believed to be relevant.

Saying I'm a libertarian ain't a controversial statement. Heck saying you are a libertarian might as well be a more fruity way of saying independent.

The left/right wing model sucks. It forces you to chose a side based on a handful of issues that you might have mixed opinions on.

For instance, a friend of mine identifies as left wing but this is mostly due to LGBT rights and abortion rights. Nearly all of their other beliefs are Republican. They want a strong border, they value nationalism over globalism, and they prioritize gun rights with a desire to ban marijuana usage. But, their opinion on gay rights and abortion often sees them shunned by the right.

We really do need more political options.

I'm an anarchist. I think there should be no politics, no governments, and no laws (or at least some laws I disagree with should go away). <----- If the only way to achieve that is by anarchy, then I'm an anarchist.

Couldn't possibly have been 4 fucking years of "everyone who leans right-of-center IS A LITERAL NAZI1!!!" Goddamn assholes

I don't know why more people don't just say they're independent. I've never seen anyone scoff or get indignant when I say I'm independent.

I think the problem is that they boil down their political lean based on one specific issue, and sometimes that issue is "which way are you going to vote", which doesn't mean much. I haven't voted conservative in the past, but many of my views are conservative (or at least they are now, due to the rise of the Trans left).

That said, I don't think that's a new thing. Get a full list of beliefs from most people, and they're probably straddling the line.

Politics have always been like that. Which side you pick could be based off of a single point. For example, throughout American history, Catholics have had a bit of a conundrum, since the Republican party was always vehemently anti-Catholic, and the Democratic party was always militantly racist. But, of course, the protection of the True Religion comes first, so the Catholics were generally Democrats.

Interestingly enough, during that time, the Republicans were known as the liberals, and the Democrats were the conservatives. The Republicans, ironically, haven't changed much since then, which is why they are now called "conservatives", while the Democratic party as we now know it really only started to exist during the time of the Great Depression, making them the liberals and the Republicans the conservatives.