Believing Marxism to be “fatally flawed” because you completely misunderstood his works to the foundational level is silly though, right? Marxism isn’t literary fiction or anything, where you can apply Death of the Author and write about your own personal meaning from the text, Marx was very clear both in writing and in speeches, and Marxists have studied and built on his original body of work.
You don’t have to take it from me alone, Marxism is extremely thoroughly documented and understood, flexible, adaptable, and widely discussed.