People who denounce theory denounce revolution. It's plain and simple. Back in pre-revolutionary Russia, the SRs declared "an end to theory" as a unifying factor to be celebrated, and declared assassinations "transfer power." This is, of course, ridiculous, theory is important because it is useful despite disagreements over it, and assassinations do not "transfer power," but create a void filled by those closest to it, always bourgeois, never proletarian. The Bolsheviks ended up being correct, that theory, discipline, and organization is what brings real revolution, and the SRs have mostly been forgotten. I recommend reading Revolutionary Adventurism.

It's important to recognize that Westerners have an implicit desire to maintain the status quo, having been taught all our lives that we have the "best possible" system yet. The western leftist idea of "no true Marxism yet" fits conveniently with that narrative, it's deeply chauvanistic and moreover anti-revolutionary. Looking at the most popular trends of Marxism in the west, we see many Trots and "orthodox" Marxists, some of the least successful in producing real revolution globally, while in the Global South Marxism-Leninism is dominant.

The "book club" Marxists are equally dangerous as the "adventurist" Marxists (or Anarchists, if you prefer). It is only through uniting theory with practice that we will succeed. You cannot be anti-theory and you cannot be anti-practice, you must unite both. I want to commend your discipline in not speaking up, one of the guiding principles of Marxists is "no investigation, no right to speak." Muddying the waters with low quality input is pollutant, asking good questions and practicing self-restraint when speaking on what you don't know clarifies the waters of discourse.

I highly recommend reading Masses, Elites, and Rebels: the Theory of "Brainwashing."

To add on to what else has been said, you can just be blunt and obnoxious about it. Tell them "If a bunch of barely literate peasants in China can figure out Kapital on their own despite it being written in another language, you can read a pamphlet or two."

People smarter than anyone alive have done more in worse conditions and did us the courtesy of writing down what worked and what didn't. The Bolsheviks, Black Panther Party, anarchists in Civil War Spain and Nazi Germany, etc. were in life or death situations trying to mobilize leftwing revolution. The least anyone calling themselves a socialist can do is read what they wrote. If you say "I don't need to read theory because it's just a book club," you're being an arrogant, egotistical asshole.

We also live in an age where there are audiobooks and videos that will read this stuff to you for free, something our predecessors didn't have. People with disabilities have used these tools to help them understand theory when they struggle with reading. There's really no excuse.