re: Has there ever been a study or theory on why conservative like memes more than liberals?

As the saying goes: there's a grain of truth in every joke. It's not impossible for liberals to be funny, but as they've increasingly embraced identity politics, being offended, cancel culture, etc., they've necessarily cut themselves off from the ability to laugh at themselves or others in a good natured way.

Conservatives can get a good natured laugh out of being called "deplorables" or identifying with what should be an insult (to the Left), like the Aryan looking guy or some variation of toxic male who replies to liberal, hyperbole/threats with, "Your terms are acceptable." Being able to laugh along with jokes turns perceived weakness into strength, which frustrates the Left in their attempts to win the meme wars. The Left are less successful at embracing imperfection because identity politics requires them to be offended. They can't laugh along, and therefore treat humor like a zero sum game where there must be a loser. Because they insist on taking offense to traditional or conservative values, they open themselves to being painted as irrational and ill-humored, as depicted in various triggered, wojak, NPC and similar memes portray them.

Not all memes are intended to be funny, but the Left isn't very successful here either because of their reliance on language games to push liberal agendas and subvert old meaning. They change the definition of vaccine, of gender/sex, or use phrasings like "mostly peaceful protests" for allies like BLM in ways that stretch truth. This opens up a wide array of ironic conservative memes that highlight inconsistencies or hypocrisy. The Left cannot target conservatives the same way because conservatism in the US is aligned with traditions like working hard, appreciating freedom, following moral codes like religion, and arguably what has stood as common sense. It is certainly possible to disagree with some traditional opinions, but it is far more difficult to mock them in a meme that has viral potential without being mean spirited. I'm not sure the Left can combat these ironic style memes at all because they're based on attempts by the Left to distort truth or redefine society, which automatically puts the Left at a disadvantage since the Right doesn't do that.

The Left is kind of reduced to ridiculing the Right as unintelligent MAGA types and/or conspiracy theorists, but rarely gets past that. This tactic works in some ways, like making some conservatives keep their head down to not get cancelled, but it is tedious as far as memes go and lacks viral staying power. And it lacks the brilliant memetic precision of something like the NPC, which gains new life every time new talking points come out in the MSM to give the NPC something new to be mad about.